Scuttling and climbing, as all crabs must be. (Seriously this rules. the only critiques I have are the color saturation on the level backdrop. And that's just personal beef.)
The mechanics? The way the level design encourages player interaction and exploration? The addictive process of trial and error to find keys?! The claw mechanics? Mario reference? the CRAB SPRITE?!?!?! LEVEL SELECT MENU?! Platformer. Heaven. I love this.