Codis Naturalis
A turn is simple: play a card from your hand then draw another. The layering mechanic is where the strategy enters. When you play a card it must overlap the corner of one or more cards that are already in play. Each corner can contain symbols that represent different species or scoring bonuses, so as you build your tableau you may have to cover symbols in order to play a more important card. In order to purchase gold cards (which provide points) the indicated symbols must be visible in your play area.
Game end is triggered once a player reaches 20 points. Finish the current round and let each player take one additional turn. Score points based on played gold cards and public and private scoring objectives. The player with the most points wins!