Nice gameplay! I like how the artsyle is very consistent and the stealth mechanics are pretty great! My only complaint is it was hard to tell which boxes are rigidbodies and which are static. I think having a different texture (with arrows pointing in both possible movement directions?) for them would fix that. Great sound effect work also!
Also, minor nitpick, it's hard to tell when you've picked up the backpack at the beginning. Maybe just having a backpack sprite that appears on the character? (or in the corner of the screen?) would make that a bit more clear. Super optional though.
Anyways, good game! Very well put together and fun to play!