Quirky and addictive
Pros: Solid, simple mechanic, addictive gameplay, challenging but not frustratingly impossible. Fantastic music. Easy on the eye.
Cons: It can feel a little arbitrary when the level prevents you from climbing, or a spike is positioned in such a way that it makes it impossible to climb.
Overall: Great fun, could easily spend more time than is healthy playing this, I think the 'pure' highscore mechanic suits the game perfectly, although I don't think there'd be the same drive to play if there weren't a leaderboard. Does what it says on the tin, really. The explosion ability is a bit redundent, I think the next step for this game would be making the blocks and fish destroyable with the explosion, and have a points value on that, would give the game a whole new level of depth without too much changing.