First off, excellent tutorial. Not only was it step-by-step for the player, but you even had isolated spaces where the player could perform each action. Brilliant!
I enjoyed the music but wasn't sure if it fit or not, personally. The gameplay was fun and rather challenging. I didn't see much use for the grapple other than getting from one end of the map to the other. Also, very nicely done mini-map. Kudos for that. I will agree with what Inglo said about there's really no incentive to move beyond one patch of the map. You can bunker down and sacrifice all others, really, at no cost to yourself. Maybe if each patch spawned 1 type of plant or some sort of variability? Dunno.
All in all, a good game here!