lags like hell.

Interesting gameplay concept, the jumps and controls felt slightly finicky though so it was difficult to complete the levels. 

You should mention in the instructions that right click is used to switch players, wasn't entirely obvious at first.

Got stuck on the second level - block against wall and couldn't pull it off of it.

Graphics/models look nice
good use of theme
good puzzles (other then the got stuck issue)
could have used some sounds/music
had a few cases there the animation state of the character appears that it was not correctly updating.  Character was walking around in the 'pushing' animation when not pushing.  Also had a few cases of the opposite.