I did not understand the mechanic at first. Don't hesistate to add a how to play or even a short texte message somewhere in the game. It can look cheap but it really helps when you don't have time for a tutorial and it doesn't costs you much time.
The ambience is very stressful, I don't know if it was the ambition, but it rreally is with the sound of the mechs in the background.
The shoot was fun, it just needs some more feedback when it hits something.
Sadly I was blocked so I could not go further as I did not manage to open the doors with any key (please tell me if I'm missing something).
I don't know if you did all the art or not but it's cool, there's a great visual ambience here! Keep up good work!