Drag the creatures around to combine them. Update log: 1: 16 creatures. 2: 4 creatures, Instructions button. 3: Shows instructions, sprite 23 non-empty. 4: 10 creatures, can't see large-leveled creatures until you get them. 5: Made the Instructions button smaller, didn't get to finish the shading cos not in Photoshop. 6: 70 creatures.
