Thank you for the opinion, guys. I'm in the middle of exams right now, so project is kinda halted. I've made the lifebar as I said I would, just did not uploaded it yet, as it's ugly and jumpy, I mean, the size just "jumps" to the value it should show. It works, but it seems kinda bland.
The bullets need some work too, I'm not too fond of how they look, even though I'm not really looking for good graphics for now, more focused on functionality.
And I already have some idead for the rest of the level.
Spikes, a real puzzle involving buttons and moving gates, a clich�d easy one, and a hard one later (that maybe is too hard for a game with that pace).
Maybe the boss of the level shooting someone(another square thing...oh god, sorry...) while the player solves the puzzle, I think it will add a "real bad guy" characteristic for the boss and maybe a "real" reason for the player to want to fight him.
Some music or sounds. For now, it will be copyrighted music, but it's ok, as I don't plan to sell anything soon, but I think it will help a friend of mine that told me he'll help with these things see how I want the game to feel.
Anyway, I'll try to address the game again when I have some time in a week or two...