General Tips

You draw 1 additional card per round for each of your species, so try to have more than one species in play. Too many species are a liability though, since they might become easy prey for your opponent's carnivores. Having 3 species is often a sweet spot.

If you have a carnivore, it has to have higher body-size to attack another species (exception is pack hunting). Since increasing body-size is an expensive investment, the top priority for your carnivore should be to avoid extinction. Hurting your opponent's species is secondary.

Carnivores are not inherently better than herbivores, it all depends on the current environment, e.g. how much food is in the pond, how many defenseless species are on the board, etc.. There is a rock paper scissors dynamic for play styles: defense > carnivore > greedy herbivore > defense

Don't spend all your cards each turn, it is often better to save cards until they become more useful or needed. One specific trait played at the right time can make the difference of a huge carnivore dying of starvation or instead destroying an opponents board.

Card Tier List

Most cards are very situational, nonetheless here is a very rough tier list:

S: Cooperation

A: Warning Call, Fertile, Horns

B: Intelligence, Climbing, Carnivore, Scavenger, Ambush, Pack-Hunting, Symbiosis

C: Hard Shell, Burrowing, Fat Tissue, Long Neck

D: Defensive Herding, Foraging

2-Player VS. 3+ Player Games

2-player games are very different from 3+:

-In 2-player, the game is zero-sum and hence carnivores with intelligence are really strong (since discarding a card is no problem for attacking since your only opponent also lose one population which is also worth a card)

-For 3+ players, scoring tends to be more important than hurting one of your opponents.