Those pesky laser mice...  The platformer physics are a nice start, but could use a little tweaking. I'd start by making the deceleration/friction a little stronger to reduce how slippery everything feels and then lower the strength of gravity while the jump button is held (to allow for variable strength jumps like in Mario games).

I think those bricks are made of ice maybe... That's one slippery mouse!  Making the cats move around and be less frequent would be my recommendation as well as the ability to collect hearts as well.

Agree with the other comments about a restart option.

The controls/physics need a bit of work, and it definitely needs a way to restart the game on death, but otherwise it is very nice.