So I got bored and wanted to throw around a game idea. Basically almost every card has to eat different cards on the field to be played. herbivores eat plants, which(usually) require nothing, Wild-carnivores eat herbivores while domestic carnivores eat meat and hybrid carnivores eat both, and omnivores can eat anything. If a card survives a certain amount of turns it reproduces and adds the new card to your deck. This card has a 90% chance for its stats to be mutated slightly, and a ten percent chance for it to be an evolved form of the more primitive card. Blue fish become pirhanas, wolves become wild-dogs, monkeys become neandrethals, etc. these evolved forms function under the same rules and in some cases, can evolve further(Neandrathals → Humans). These cards arent always better than their more primitive form and can be anything from fodder(How about a real life example, Megatherium to sloths), situational but useful, to pretty damn good. There are also virus cards, attaching them to animals will make them weaker but give you a one-hundred percent chance of their off-spring being an evolved form.
This sounds like a pretty decent idea for a game. However, I think we would have to change the reproduction and mutation elements of the game. So far, I think a 90% chance of a mutation is a bit too high, even if the stat changes are mild (because sometimes, the slightest change can make a big difference). I think the chances should be demoted to 10%, and the chances of an evolution being 2%. The chances will be increased when the player plays a mutation card, or the virus card that you mentioned.
And I also think that cards reproducing should really be done through a sort of “action” card instead of a certain amount of turns surviving. I’m thinking of something like a card that allows you to choose what specific animal/plant card to reproduce.
Anyways, that’s my input. This would be a cool game to create.