Nice game! If I may make a suggestion, I find it difficult to read the board with all the different sprites. In particular, I find it hard to find cells that remain "unopened" (both marked and unmarked). It would be nice to either increase the contrast, or to have a way to highlight them (maybe through an upgrade, giving a button to "highlight unopened cells"). Also, for the final game maybe it would be nice to be able to do different builds? For instance, it would be nice to be able to play the game without rabbits (for a more manual game), or without turtles (for a more risky game), rather than them being necessary to get other upgrades.