A good start howevever few points;

1)if the crate gets pushed to the corner it's impossible to get it from there.

2)Turrets should really be dangerous, do they even aim with vertical axis?

Other than that a good game, I was amazed that something actually works on my notebook smooth. Couple hints about coding: Try to make general style functions for doors if you continue like you've done before it may be frustrating (in the end (and resulting propably to unneeded code).