Congratulations on releasing a game of this scale in such a short amount of time ! 3D game in 5 days is nothing to scoff at (I should know, since our game is also 3D, hehe).
I personally liked the shooting and locking mechanics. I just wished there was a bit more feedback when you get hit, such a camera shake and perhaps some SFX, something to tell the player : 'You've been hit, and that's bad.'
Other than that, the game lets itself play easily, the atmosphere is well done (I just wished there was more incentive for the player to get out as fast as possible, moreso than the timer. Perhaps flashing lights, scripted explosions etc ...).
Anyway, the game is very well done and has a good feeling to it, congratulations !