Okay, I've played this for about an hour, and I'm already stuck. First of all, the digital lock's code for the second gun I had to guess the order. At first, I thought the puzzle was supposed to act like a twelve hour clock because of the ??:?? hint. Instead, the code was military time (2139). Now I can't even progress. While I wont ask where to go, I think you should add more guidance after that point.
So far, I've found a single bug. When you die, collected resources dissapear. For example, If I saved then collected an hp upgrade then died, I wouldn't be able to get th hp upgrade anymore.