I actually liked your idea with FISH. Maybe you could have an objective to reach like use the smallest number of fish to defeat the larger animals. Use different combinations of smaller fish, each with different abilities.
Hey! thanks for replying. I kind of have an idea now; I'm making a rouge-like. The interpretation o the limitation is through the story: You've almost finished yourpuzzle but the smallest piece is missing. so you go to the basement to find it, where you encouter enemies or maybe even bosses
