Graphics are good, and you people managed to do quite an impressive job. I'm not a fan of Unity's postprocessing effects though, I think these effects only obscured the screen and didn't cuntribute too much. The rain was cool, the setting at the start of the game.
Now, gameplay. The idea is ok, sneaking and that stuff. I think the guards are overcomplicated, didn't realize they kind of followed you, I just thought their movement was random at first. The lights, please don't, 3 out of 5 lights didn't show up in my game session at least, or at least I guess there were lights, I just didn't saw anything. I somehow managed to get their timing or something, I actually don't know how the heck did I passed through them.
I didn't especially liked the sound department. The only music loop was tiring through the end of the game. But I loved that death sound, so ominous.
Story is ok, but I know this is one of the most difficult parts of conveying since you have little time, which ends up in short gamelenght. The "twist" at the end was fine.