Seriously Liked this!
Yeah man, this was really fun. I really enjoyed the gameplay and I loved the coin/unlock system. I think you should definitely make a split screen two player version or even an online version! As for the bugs, I did notice a few, unfortunately, I'll note some down now so you can fix them later:
-On the level 'Shaft' if you take your guys past the elevator and keep going to the right, you reach a white space and if you make your guys move into it, the game will crash your computer until you deactivate the game script.
-Also on the level 'Shaft' if you make one of your guys go into the elevator and press him up against the left wall of the elevator, he will be transported to the finishing flag.
They're the only main glitches I've found, one thing I would say though is to not have to do that tutorial level everytime you play it again.
Anyway, this is a fantastic game and I wish you all the best for your future projects!