You are right, I didn't thought of making some differences to tip the player that it's another prisoner. I did thought about implementing the boss timer, as you suggested, but I guess I forgot. I'm still learning how to properly plan a game and do the pre-production steps, so I don't have to come up with stuff "on the fly".
I will improve the game on the feedback that I received, but will not move forward with it too much, as I'm wanting to try other concepts, like, I've played some Point-And-Click games that I really enjoyed, and that type of game bring me so much nostalgia, so I will try to make one myself :)
Thanks again for your time, and don't worry about the congratulations thing :D
Btw, I played your tower defense game again and was finally able to shoot! Hahahaha xP