could you add an infinite game mode. that could expand throughout the whole universe and more.
Some idea
Maybe a character with more card to choose from
Card with effect one more than one turn, like a card that steal 8% of the enemy size at the end of 3 turns, or maybe card that do nothing but when you get three of them, it do something powerful, long casting cards to, or maybe card that add trash card to your opponent, maybe you can try to find inspiration from game like frien vs friend, where your hand of card can be affected by th opponent or slice and dice, with card with keyword effect
Maybe a passive ability where he character use the unused card of the opponent
If we keep the idea of an Infinite mod, the game need to be separated between round, for ajusting basic's card, maybe between round, player can afford multiple thing, like the player have 1 spare time, he can go to a shop where you can take one more card in your deck with some effect, or maybe take a object wich give another passive effect, maybe the player can choose to train during spare time, to gain a power or more size only for the next round. Maybe rounds can change, like the opponent having card bough in the spare time, or the place where the fight take in, making some fun effect