I like this concept a lot. The idea of using the way a crab moves sideways is really funny to me. I really like the way the controls are laid out on two halves of the keyboard. I think it really adds to the sort of disorientation of being a crab.
The actual gameplay is relatively simple but I think it's a nice little experience. I'd be interested to see this sort of expanded on and how a crab might go about other activities with this same control scheme.