First Digimon TCG promo pack teased, card effects revealed in livestream & Memory Gauge explained

An older and younger brother play the 2020 Digimon card game in Bandai's concept trailer.

In a livestream aired at 3 AM Pacific Standard Time, Bandai Namco revealed several upcoming promotional cards for the 2020 Digimon Card Game, and also showed a 2020 concept trailer for the entire Digimon franchise that revealed two more Digimon effects from the upcoming TCG. Bandai also opened an official Digimon Card Game Twitter account shortly before the livestream aired, where it gave us our first look at the product packaging for the Starter Decks "Gaia Red," "Cocytus Blue," and "Heaven's Yellow." The header for the Twitter account--which also appears as the illustration for the game's first promo pack--suggests V-mon, Liollmon, Kokuwamon, Betamon, Tentomon, Dracomon, Plotmon, Goblimon, Pico Devimon, Patamon, and Guilmon, are all coming to the card game.

The header for the official Twitter account.

The Starter Decks are on-schedule to launch in April at 500 yen per deck. The packaging states that the game is for ages 9-and-up, which is noticeably higher than the current standard for TCGs: Yu-Gi-Oh!, Pokémon, Buddyfight, and Cardfight!! Vanguard are all recommended for children 6-and-up.

New card reveals

Metal Garurumon
Level 6/Data/Cyborg
11000 DP
Entry Cost 12, Evolution Cost 4 (From Level 5)
Effect unknown.

Angemon
Level 4/Vaccine/Angel
4000 DP
Entry Cost 5, Evolution Cost 2 (From Level 3)
Effect unknown.

Gabumon
Level 3/Data/Reptile
Entry Cost 3 Evolution Cost 0 (From Level 2)
2000 DP
[Attacking] When it attacks a Digimon, [illegible] 1 of that Digimon's Evolution Sources.

Leomon
Level 4/Data/Beast Man
Entry Cost 5 Evolution Cost 3 (From Level 3)
5000 DP
[When destroyed] Summon 1 Child-level Digimon from this Digimon's Evolution Sources without paying the Cost.

Note that this is the first instance of "Summon" (召喚 shoukan) appearing in effect text.
Promotion Pack ver. 0.0 cards

These cards will appear in promotional pack ver 0.0, which are not for sale and will be distributed to "various places." Fans are encouraged to check the official site and Twitter account for more information at a later date.

The promo packs will most likely be given out as participation prizes at hobby shops that host 2020 Digimon Card Game tournaments, as an incentive for players to participate; this is how Bandai and other manufacturers have done similar promo packs in the past. Several of these cards are partially obscured or at too low a resolution to make out distinct kanji, thus the effects below are incomplete.

Piyomon
Level 3/Vaccine
Entry Cost 3 Evolution Cost 0 (From Level 2)
2000 DP
[illegible] ...destroys your opponent's Digimon... [illegible] ...draw a card).

Gomamon
Level 3/Vaccine
Entry Cost 4 Evolution Cost 0 (From Level 2)
2000 DP
[When it attacks] (Once per turn) Your opponent's Digimon's Evolution Source... [illegible] ...gets Memory +1

Tailmon
Level 4
Entry Cost 4 Evolution Cost 2 (From Level 3)
4000 DP
[illegible] Look at 3 cards from the top of your Security, return (?) as many cards as you like to the top of your Security in any order, and put the rest on the bottom.

The Security mechanic is also mentioned in War Greymon's effect text.

Agumon
Level 3
Entry Cost 5 Evolution Cost 0 (From Level 2)
3000 DP
[When it Enters] Destroy 1 of your opponent's 3000 DP or less Digimon.

Gabumon
Level 3/Data
Entry Cost 4 Evolution Cost 0 (From Level 2)
3000 DP
[On-Entry] 1 of your opponent's Digimon's Evolution Sources, [illegible] from the bottom.

Patamon
Level 3/Vaccine/Mammal
Entry Cost 4 Evolution Cost 0 (From Level 2)
2000 DP
[illegible] When... [illegible] 1 or less of your Security, [Recovery 1... [illegible] ...1 card from the top of your deck to the top of your Security.)

Livestream content

During the official Digimon livestream Bandai representative Goto-san described the TCG as "a game where both kids and adults can enjoy battling and collecting," and presented several slides clarifying elements of the game. Digimon begin as a "Baby" level card that features a Digitama, Baby I, and Baby II Digimon in a single illustration, which is considered Level 2. They then evolve to Child, Adult, Perfect, and Ultimate, with cards being overlayed on top of one another so that the colored text of each card is visible beneath it. Level 2 Digimon can also have inheritable effects like higher-level ones, but the example card was not legible.

Metal Greymon
Level 5/Vaccine/Cyborg
Entry Cost 7 Evolution Cost 3 (From Level 4)
[When it attacks] [Once per turn] When this Digimon destroys your opponent's Digimon by battle, put this Digimon in the Active state.

Greymon
Level 4/Vaccine/Dinosaur
Entry Cost 5 Evolution Cost 2 (From Level 3)
4000 DP
[Security Attack +1] (When this Digimon attacks Security, increase the number of cards it flips over by +1)

"You can send out your favorite Digimon right from the first turn!?
Your opponent's marker moves proportionate to the cost paid.
Exceed 1 and it's your opponent's turn.
Enjoy simple, innovative & dynamic battles."

Goto also gave a brief explanation clarifying the Memory Gauge system. Players can actually play Digimon of any level right from the first turn of the game, but this will move the Memory Gauge toward the opponent equal to the Digimon's Entry Cost, and if it surpasses the "1" mark it ends the current turn. This means that you could theoretically play a Level 6 Digimon like War Greymon right on the first turn of the game--but you would be giving the opponent a massive amount of Memory to spend, so they would be able to play even more Digimon than you without their turn ending.

The stream also partially revealed the Starter Deck print of Gabumon, which has a different effect from both the promotional card and the version seen in the trailer. Agumon is unchanged from the website version, and Patamon's text is illegible save for the fact that it happens when it attacks and modifies the opponent's DP. The cards are illustrated by Watanabe Kenji and As'maria, two of the franchise's longest-serving artists.

Gabumon
Level 3
Entry Cost 3 Evolution Cost 0 (From Level 2)
2000 DP
[During your turn] (Once per turn): When your opponent's Digimon's Evolution Source is [illegible] until end of turn, this Digimon's DP gets +1000.

At this point, it appears Digimon cards can have two kinds of effects: those written in the colored effect boxes at the bottom of a card, and those in transparent boxes imposed over the artwork. Only colored effects appear to be inherited by evolutions, which is how Metal Greymon and War Greymon were portrayed on the official site, as well as Leomon and Gabumon in the new trailer.

For example, the promo print of Agumon has a transparent box effect that destroys an opponent's 3000 or less DP Digimon when it enters play, while the standard Agumon's colored effect gives it +1000 DP during its owner's turn. The former is the kind of effect a game designer wouldn't want players getting to recycle all the time, while the latter is much more balanced as an inheritable ability. Some of the effects already allow powerful combinations; combining the entire Starter Deck War Greymon line together creates a Digimon with 13000 DP that can break 4 Security in one attack while also destroying an opponent's Digimon by battle.

2020 Digimon TCG will "revolutionize" card games, War Greymon & Metal Greymon's effects revealed

"In April 2020, that Digimon card game returns!"

Over January 20th the official Digimon homepage was revamped in both Japanese and English, accompanied by a new Japanese-only website for the 2020 card game. This is the first such Digimon Card Game website since the closure of the Digital Monster Card Game Alpha homepage in February 2008, and it reveals several key details about the game's rules, as well as new card effects.

Promising the return of "that" Digimon card game, the main page ad gives us our first look at both the card back and Metal Garurumon, the face of one of three 500-yen Starter Sets available when the game launches this April. ("That" game likely refers to the popular Digital Monster Card Game that ran in Japan from 1999-2006, which over the past few years has seen new collector's sets published to coincide with the Digimon Adventure anniversary project.) Of note is that Bandai chose to publish the TCG information in both English and Japanese, even though the TCG site itself is Japanese-only. Bandai may be considering a future English localization--their popular Dragon Ball Super TCG became infamous in the English-speaking world for pulling players away from Cardfight!! Vanguard and other games, and with the western trading card market becoming increasingly open to games outside the "big three" thanks to Super and the Final Fantasy TCG, 2020 would be an ideal time to market a new game.

The three Starter Decks previously revealed are named Gaia Red, Cocytus Blue, and Heaven's Yellow, and will each contain 16 kinds of cards. The actual total number of cards in each deck is unknown. Typically if a game has 16 unique cards per starter deck, then the total deck size is 50, but depending on how many copies of each card is included, this could vary. The Starter Deck names come from the Japanese names of each featured Digimon's special attacks: Gaia Force, Cocytus Breath, and Heaven's Knuckle.

Aside from the Starter Decks, the 2020 TCG website is a part of Bandai's Carddass brand network, meaning the TCG will likely be distributed through both traditional booster boxes and trading card vending machines like past Digimon games.

The Memory Gauge
The 2020 Digimon Card Game webpage states that the TCG's "Memory Gauge" system will revolutionize Trading Card Games, and it certainly provides a unique spin on the standard mana formula. Take a look at the cards below:

The Memory Gauge is a resource shared by both players, used to pay costs. It starts at 0, but each player can voluntarily increase it at the expense of immediately ending their turn. Because it's shared by both players, the opponent increasing their Memory benefits you--if you have 2 Memory and the opponent has 3, then either player can play Digimon and use abilities with a cost of 5. This reduces the advantage either player gets out of going first or second, because Memory is necessary to evolve into or directly play Digimon, so both players are incentivized to give each other more Memory in order to deploy their respective strategies. Even though the player going first will be the first one to evolve their Digimon, the player going second will have more Memory available on any given turn.

This makes the Memory Gauge a fundamentally different kind of resource system from those found in Magic: The Gathering or Pokémon. Instead of having to draw a specific card dedicated to being a resource and play it each turn, the player in Digimon 2020 is given guaranteed ways to increase their resources and the possibility of receiving even more from their opponent. This is more akin to the Play Points found in Shadowverse, but with the addition of mindgames over whether or not to give the opponent more Memory on a particular turn in order to be able to pay higher costs on subsequent turns.

While the webpage says the gauge can be increased by paying the gray "Entry Cost" (登場コスト toujou kosuto) at the top left corner of a Digimon card, how this works isn't clarified. The full rules of the game are to be published in the April issue of V Jump on February 21st, and will likely leak a few days early as the previous issue did.

New card reveals

War Greymon
Level 6/Vaccine/Dragon Man
12000 Power
Entry Cost 12, Evolution Cost 4 (From Level 5)
[During your turn] For every 2 Evolution Sources, this Digimon gets «Security Attack +1». (When this Digimon attacks Security, increase the number it flips over by 1.)

Metal Greymon's effect is just barely visible beneath War Greymon's, used to confirm V Jump's statement that evolved Digimon inherit the effects of the cards beneath them.

Metal Greymon
Level 5/Vaccine/Cyborg
[When it attacks] [Once per turn] When this Digimon destroys your opponent's Digimon by battle, put this Digimon in the Active state.

This is speculation, but War and Metal Greymon suggest several things about the game mechanics. The first is "Security," which based on its inclusion on a high-level card seems to be important to the game's win condition. Security is probably a mechanic similar to the Shields of Duel Masters or Life Cloth of Wixoss; cards which protect the player from direct attacks, and when all Securities are removed, either the player loses or they'll be vulnerable to a direct attack that will win the game for their opponent.

Note that «Security Attack +1»'s rules text states it "flips over" (めくる mekuru) one more. (Using the counter word 枚 mai, which is used for long flat objects like trading cards.) This verb is generally used to mean turning something to its opposite side--a page, a card, and if you remember the Nintendo eShop game Flip Wars, in Japan it's called Battle Sports Mekuru. While mekuru can also be used to mean "tearing off," the word suggests to me that Securities are cards turned face-up, which is exactly what happens not just with Shields or Life Cloth, but also with Life cards in Z/X and Damage Checks in Cardfight!! Vanguard. Moreover, Securities are counted with the counter word 枚 mai which is used to count long flat objects, including cards. In updating Digimon's game mechanics for a modern TCG audience, it wouldn't be surprising for Bandai to follow this design trend. If all this follows, that means War Greymon has the potential to flip two or three Securities in one attack.

The question is, why are Security cards turned over at all? The cards being turned face-up suggests there's important information both players need to check. In other games that do this like the aforementioned Duel Masters, Wixoss, and Z/X, it's to check if the card has a special ability that resolves when revealed. (Shield Triggers for Duel Masters, Life Burst for Wixoss, Ignition effects for Z/X.) In those games these abilities do things like instantly summon the monster with the ability, use an instant effect without paying its cost, or draw additional cards for the defending player. Security cards are probably normal cards placed randomly from the player's deck, some of which will have abilities that interfere with the opponent's battle phase to prevent one-sided games.

Metal Greymon's effect is interesting because it mentions the term "Active," which is also used in Bandai's Dragon Ball Super TCG. In DBS "Active" refers to vertically-oriented cards (portrait position) which are the opposite of horizontally-oriented "Rest" cards (landscape position) equivalent to Magic's "untapped" and "tapped" states, or Cardfight!! Vanguard's "stand" and "rest" positions. If this is what Bandai's going for, Metal Greymon can attack a second time in a turn provided its previous attack destroyed a Digimon--so it can't use the effect by destroying a Security card, but it could destroy a Digimon and a Security rather than having to choose between attacking one or the other.

And since War Greymon inherits the effects of the cards beneath it, a War Greymon with both Agumon and Metal Greymon beneath it gets +2000 DP while attacking, can attack twice in a turn by attacking a Digimon, and breaks an additional Security card. (It will not, however, gain 4000 DP total. Agumon's effect only applies "while" it is attacking, not until end of turn, so the initial power boost goes away at the end of the battle, then reactivates on the second attack.)

[Update: Agumon's effect on the official website has changed since its appearance in V Jump. The revised text simply gives it +1000 DP during its owner's turn.]

Something else to note is that at the website's higher resolution, Agumon's Evolution Cost states "From Level 2." While V Jump merely stated that Digimon would evolve from Digitama in the card game, this implies that players will actually have to play Level 1 and 2 Digimon first, like Botamon and Koromon--traditionally the Baby I and Baby II stages of a Digimon's life cycle are omitted from the card games because they are not capable of battling in the original virtual pet toys. Having Level 1 and 2 Digimon in the game would have a significant impact on gameplay, with a player potentially going into Level 3 with 4 Memory already available. There are other possibilities, like first and second levels being condensed together in some way, but nothing definite can be said until more is revealed.

Bandai announces 2020 Digimon Card Game, Starter Sets only $5

Launching April 2020: War Greymon, Metal Garurumon, Angemon starter decks.

"Aim to be the strongest Digimon Tamer with the Digimon TCG!!"

Three years out from shutting down their Appmon collectible card game, Bandai announced the 2020 Digimon Card Game in V Jump magazine. Set for a Spring launch and paired to the new Digimon Adventure series airing at 9 AM Sundays on Fuji TV--the same timeslot the series debuted with in 1999--the new Trading Card Game puts Digimon's classic monsters front and center. This TCG appears to be largely unrelated to the franchise's past Japanese TCGs, with a resource system, "colors" for each Digimon group evocative of Magic: The Gathering and Duel Masters, and a single unified attack power instead of the rock-paper-scissors stat system used in the 1999 Digital Monster Card Game and 2006 Digital Monster Card Game Alpha.

V Jump highlights the illustrations as a major selling point: every card appears to have a custom illustration commissioned just for that card, with no stock art as seen in past games. According to the magazine, players grow their Digimon partner from a Digitama/Digi-Egg all the way up to Ultimate level, and Digimon "inherit the effects" (効果を受け継ぐ) of the cards they evolved from. For example, Agumon has an effect that gives it 2000 additional DP while attacking, and if it evolves to War Greymon, War Greymon will also have Agumon's effect in addition to its own.

(Note: "Ultimate" is the name for the sixth-level evolutions in Japanese, equivalent to "Mega" in the English dub, one level below "Super Ultimate"/"Ultra" level.)

Agumon
"When it attacks: During that battle, this Digimon's DP gets +2000."

War Greymon
Effect unknown.

Each Digimon has two types of cost found in the top left of the card: the colored cost, placed lower on the card, is its Evolution Cost, which must be paid to evolve into it. The gray cost, found in the top-leftmost corner, is unclear. While the magazine scans are high-resolution, they aren't high enough to distinguish the distorted kanji on the gray cost; it may be a "deployment" (展開 tenkai) cost, as the article also mentions "deployment" as an element of the game, but the shape doesn't look exactly right.

Digimon also have a level next to their name, identifying their evolutionary level. Like in the old Hyper Colosseum TCG, this is a number rather than a name, with Child/Rookie-level Digimon being level 3, Adult/Champion Digimon being 4, and so on. All level 3 Digimon have an Evolution Cost of 0, allowing them to be played for no cost.

In addition to the numbered level, the Digimon's formal level name is listed in smaller text in the bottom right corner of its name box, as well as its attribute (Agumon and War Greymon are Vaccine-attribute) and type. (Reptile, Dragon Man, etc.) To the right of each card's name is its serial number and rarity, with DG-000 Agumon being a Rare and ST1-10 War Greymon's rarity being illegible. War Greymon's effect box is blank, likely to keep it a secret for the next issue, which promises to come out with the detailed rules and card effects.

Most important of all is that every Digimon in the new TCG has a "color," which is identifiable both by the color of their Evolution Cost, and by the color of the box containing their name on the lower part of each card. Each Digimon can only evolve into a Digimon of the same color (同じ色同士だったら、好きなデジモンへ進化できる！"If their colors match, you can evolve into the Digimon you like!") and so far three colors have been identified.

• Red has a strong attack-focused style of play, featuring Dragon Man and Dragon-type Digimon and abilities that increase their DP. (The attack stat.) For example, Agumon's effect gives it +2000 DP during the battle it attacks, allowing it to attack with 4000 total DP even though it can only defend with 2000.
• Yellow is control-focused, featuring Holy Beast, Fairy, and Angel-type Digimon with effects that decrease the opponent's DP. The sample Yellow Digimon is Patamon, whose base DP is just 1000, but its effect is illegible at the scan's low resolution. Patamon's effect does do something to modify DP, but it seems to be in a 3-digit increment rather than 4--possibly a 500 point decrease or increase.
• Blue stresses "expansion/deployment" with Beast, Beast Man, and Beast Knight-type Digimon. It "reigns over the board" by discarding the opponent's cards. Like Patamon, Gabumon's text is mostly illegible. 

The card game will launch in April 2020 with three Starter Sets, one each for Red, Yellow, and Blue, respectively featuring War Greymon, Angemon, and Metal Garurumon. (This may refer to the cards featured on the cover of the box, rather than implying Patamon's deck will stop at level 4.) A booster pack expansion will follow soon after. The next issue of V Jump magazine will feature more detailed rules and card effects. 

Each Starter Set will retail for 500 yen plus tax, approximately $4.54 at current exchange rates--note that this is an incredibly low entry point for the game compared to its competitors. Cardfight!! Vanguard's standard Trial Decks cost 1500 yen, Future Card Buddyfight 1000~1500 yen, Yu-Gi-Oh! 1000~1200, Duel Masters 900~1500, and Pokémon 1556 yen. Even Appmon starter decks cost 950 yen back in 2016, and the closest products on the market now are Wixoss' fifth-anniversary 555 yen decks, and Vanguard's 500-yen reprint-focused Start Sets.

Of note is that the 2020 Digimon Card Game is launching only a few weeks after Bushiroad's otaku-targeted Rebirth For You TCG, and far ahead of their upcoming general-audiences game Dominator. The low entry point is an aggressive way for Bandai to compete with Bushiroad and Konami, both of which have suffered difficulties in the Japanese market in the past several years. Bushiroad saw both its Monster Collection and ChaOS TCGs fold while Luck & Logic fell into obscurity in Japan and shut down internationally alongside Dragoborne, and Konami saw what was supposed to be a major boom period turn to bust as returning players coming in from the newly-launched Duel Links mobile app subsequently turned away from Yu-Gi-Oh! in favor of other games after being alienated by the onslaught of new mechanics not found in the nostalgia-focused Links.

Although much ado has been made about digital TCGs like Shadowverse, Bandai is actually one of many Japanese manufacturers turning back to making paper games after getting burned by the market saturation of digital TCGs. Only Shadowverse, Hearthstone, and Bandai's own Zenonzard survived Japan's three-year digital TCG bubble, with other games like Takara's War of Brains and Sega's Code of Joker shutting down in 2018 and 2019. Even Zenonzard may not come out of this unscathed--the game's Japanese following is one-sixth the size of Shadowverse, which keeps pulling players away from other mobile-based TCGs, and will likely continue to do so as the new anime series helps it snowball its advantage as the market leader.

Ikeda Yoshimasa, of Japan's largest national hobby chain Card Kingdom, recently noted on Twitter that the average age of Yu-Gi-Oh!, Duel Masters, and Pokémon players has shifted over time towards the mid-20s and early 30s, with the bulk of each game's player base being adults. With Digimon Adventure reclaiming its Sunday morning timeslot--the ideal slot for children's programming in Japan, where that time isn't taken up by church services--the card game will have ample opportunity to recruit young players, and face comparatively little competition from its historical rivals. In fact, its biggest competitor may be the Shadowverse franchise, which will be premiering a new shōnen anime series in April 2020 on TV Tokyo, and won't have to deal with the typical obstacles of getting a child into a hobby shop. This will be something of a test for whether or not digital and analog TCGs truly compete against one another, and if they can actually "steal" players in the way that analog games poach from each other.

With the new Digimon Adventure TV series attempting to once again milk the nostalgia of core fans, but also appearing on a child-friendly timeslot, the 2020 Digimon Card Game is likely trying to bring in a mix of brand-new players and the nostalgic old guard to guide them. The Japanese Digimon TCG grew up with its audience--for many fans between Frontier and Savers, it was the franchise--but never reached the point where discrete age divisions could viably exist to allow children and adults to compete separately among their peers, as they had in Pokémon and so many after. Provided that the game is well-received, this would be Digimon's chance to catch up in building a community of players, bridging the long gap between the end of its original run and present-day revival.

Lingering questions

How do you win the game?   
Battle is fairly obvious thanks to the way Agumon's effect is worded. The effect gives additional power "when attacking," which implies the turn player declares attack(s) on their turn and wins a battle by having greater (or equal?) power to the opponent. But what is the result of winning a battle? The "score/point gauge" system used in Hyper Colosseum was not well received when it was reused in Appmon, and cards don't seem to have an equivalent to the Lost Points stat that would make it possible to use.

Most TCGs in Japan now have a non-abstract win condition represented by cards--destroying the opponent's "Shield" or "Life Cloth" cards like in Duel Masters and Wixoss, sending cards from the top of their deck to their "damage" like in Vanguard and Final Fantasy, or taking "Prize Cards" as in Pokémon. Other games like Lycée and the long-dead Bankett! have the player discard cards from their deck equal to the damage taken, so that players only lose when they deck-out, but Digimon's attack numbers are in the thousands range rather than single-digit.

What role does card position play? 
In most TCGs you "tap," "rest," "exhaust," or perform some other action that turns a card horizontally to declare attacks or use certain effects. Yu-Gi-Oh! and Digimon were originally the exception, with Yu-Gi-Oh! using vertical and horizontal position to differentiate "attack mode" from "defense mode," while Digimon largely ignored position, but this was to their detriment. Gameplay feels much less immediate when players have no tactile feedback and are simply taking turns declaring their attacks and subtracting imaginary values, without actually moving cards around the board--tapping and untapping works because it's a physically meaningful action the player can take that immediately changes the meaning of the cards on the board, and because they feel incentivized to take it each turn to progress the game state.

How big is a deck, and how many copies of a card can you have? 
The low cost of the Starter Sets could imply a smaller deck size akin to past Digimon card games. If Digimon are supposed to go through life cycles then it could be a 30-card deck like in HC and Appmon, but if not then 40, 50, and 60-card decks are all standard in different games, and 3 or 4-ofs are the typical maximum. In general ~50 seems to be the magic number for ensuring draw effects aren't too powerful.

How are costs paid? 
Magic: The Gathering had players tap "land" cards to pay for mana costs, Pokémon had them attach "energy" cards to their monsters, Duel Masters and Wixoss both use a system where any card can become mana/energy--but Wixoss added the wrinkle that energy had to be discarded to use it, and brought in a whole lot more ways to get or lose energy as a consequence of that. Vanguard instead had the player's damage function as their means of paying costs, but had a similar evolution mechanic to Digimon with a simple rule that the player could only "ride" once at the start of the turn and only to a card of the same or greater level. The fact that there is a resource system at all is a relief in its own right, as the lack of one can seriously disrupt game balance in a TCG.

How many Digimon can you have? 
The wording in the article seems to imply you only get one partner Digimon, but it's not without precedent for players to control up to three in a Digimon TCG (as in the alternate "Ultimate Battle" format for the 1999 game, or in Alpha's general rules) and the other games on the market all revolve around having anywhere between five and an unlimited number of monsters to attack with.

What are the comeback mechanics?
 One of the biggest weaknesses of past Digimon games was that there were no comeback mechanics baked into the rules, which incentivized players to stop their opponent from playing the game as much as possible and created snowballing situations where whoever got the lead first could keep it forever. Players generally do not enjoy one-sided games where there's no opportunity to mount a counterattack. Vanguard had the player's damage act as their mana, as well as "Limit Break" abilities only usable when they had 4 or more damage available, Wixoss had the player's defeated SIGNI (monsters) and broken Life Cloth go to their energy zone to make the losing player able to use more card effects each turn than the winning player, and Duel Masters put broken Shield cards directly into the player's hand to give them card advantage.

What can you do on the opponent's turn? 
In general, TCGs have gotten more interactive over time. One aspect the Pokémon TCG gets criticized for is that it never got more interactive than using Power Spray back in 2008, and once Power Spray rotated out the game never revisited the idea. Vanguard, Wixoss, Buddyfight, and even Rebirth, all introduced different cards and mechanics that could be used on the opponent's turn, whether that was as simple as discarding a card with a defensive effect to nullify one attack, or as complex as using your own card effects in response to them playing a creature or attacking.

What chance elements are there? 
One reason for the success of Weiss Schwarz, Duel Masters, Vanguard, and Wixoss, is that each of these games use "trigger" effects--secondary effects of cards that activate when they are revealed during the attacking or defending step, and give an advantage like drawing an extra card, dealing extra damage, untapping a card, or summoning another creature. Very competitive but low-chance games like Dimension Zero failed in part because they didn't have enough chance elements. These aspects don't have to be overwhelmingly powerful, they just need to be significant enough to surprise players, make the game fun for casual fans, and give competitive ones an unpredictable element to take into account when planning their strategy.

How many total colors are there, and how balanced will they be? 
"Game balance" is no longer the meme it once was. Vanguard has ~20 viable and distinct deck types in any given format, new Wixoss players are told to play whatever they want because of the strides the game goes to balance both its colors and individual LRIG characters, and Oko notwithstanding Magic has come a long way from 1993. The prognitor of all TCGs used to be infamous for making blue objectively superior to every other color, and in legacy formats it still is...which is why players prefer Standard format, where other colors can actually top. In Pokémon Welder saw a lot of hate for how much better it made Fire over the other types, and the game as a whole still sees the same colorless (or functionally colorless) tools being shared across all of the different deck types. 

Hardcore players aren't going to stand for a low-diversity format in a brand new game. At a bare minimum all colors in Digimon need to have at least one viable deck, and ideally you would be able to build a War Greymon deck just as viable as a Gaioumon deck despite them both being Red. Of note is that Red, Yellow, and Blue are three of the six colors found in Battle Spirits, which Digimon helped bring back from near-cancellation with a series of highly successful crossover sets starting in 2017 and continuing up to February 2020. It's entirely possible Bandai has members from the Battle Spirits design team working on the 2020 Digimon card game, with the remaining colors being Green, Purple, and White. It is interesting that they did not go the obvious route of defining "colors" along the lines of Fields like Dragon's Roar, Nature Spirits, and Virus Busters, but Fields are a relatively obscure bit of Digimon lore and not the most approachable idea to design a game around.