Very creative way of re purposing a health mechanic. Nice job.

This game has a really great mechanic that I haven't really seen before in a game. I like how you use hearts as a way to combine all of these different puzzle mechanics. From opening doors to shooting bullets, everything is connected. I'm surprised by the amount you are able to squeeze out of this one mechanic. My only main complaint is the amount of waiting that you have to do to heal, especially in the late game. Other than that, this game is excellent. Amazing work!

Interesting, requiring certain amounts of health for passing thru locked doors. Perhaps this could be expanded to using health as a currency in general.

Right now the collisions seem to simply subtract your velocity, which causes a stuttering effect - collision events could be used to align the character pixel-perfectly.

Interesting puzzle. I didn't realize that health regenerate until I read the comments so I was stuck in that room in the top right of level 2. 

The one thing I would improve are the controls. They weren't really satisfying and seemed unnecessary to the puzzle solving since the spike obstacles weren't the most interesting obstacle. I feel the game would work better with grid space movement.

Anyhow, I really like the idea, good job :)

If level 2 could cover only 2 doors/ keys, it would feel better. Then move current level 2 to level 3's slot and current level 3 to level 4's etc. It wasn't entirely clear that health recovered when staying still. Despite those 2 complaints and the mechanics are clever, simple, and engaging!

Only realized later on what the mechanic was (red doors open when HP matches, yellow doors open when enough keys are had and uses up keys), feel like the challenge spike in level 2 was a bit too much though. Agree with comments below that a digital grid based movement would help things as the hitboxes on the spikes seemed a bit too big for comfort. Very interesting mechanic though and taking a hit to progress seems like something unexplored much in games!

This game is a very interesting puzzle game that definitely builds onto itself very well. The addition of a different ways to use and manipulate your hearts is really cool. The level design is also put together well for the most part. I enjoy how each level made me think in a different way. It was very stimulating. However, there were several instances where the level design felt more punishing than rewarding. My particular problem is with level 2. There was a section with 2 rows of spikes and a small cap in the middle (featured in the bottom left of the screenshot). Until I figured out I could run over both without being damaged by both, I constantly would stop in the middle, and would have a tiny pixel on one of the spikes and would keep dying. If you were to make the "invulnerability frames" more noticeable (the player flashes) and extend the invulnerability frames a half a second, then that experience wouldn't of been so grueling. I think I played level 2 10 times. Also, in the screenshot, if the player picks up a key before he gets to this key in the locked room, it becomes impossible for the player to pick up that key. It may have been intentional or just an oversight, but either way, it's really annoying to be forced to play a level completely over again (especially this one since i found level 2 to be the most frustrating) just because he picked up a key in the wrong order. Other than those complaints, this was a really well designed puzzle game, good job!

Cool game! It took a while at first to understand that the hearts are used as inventory, and that the hearts are regenerated when standing still. But once I got hang of it, the game had some really interesting puzzles. This game clearly needs some polish, but it has potential. A suggestion is to use a grid-based movement. There were plenty of times where I unintentionally went on spikes and had to restart the level. I would also like to see smaller levels that fits on the whole window.

Had to admit, I was pleasantly surprised~ You truly took advantage of this mechanic with very clever puzzles! I didn't figure out that I could refill health by standing still, but after that, it was pretty interesting~ This definitely has lots of promise, well done!

I really like the idea of using health  as the main mechanic for puzzles, all though it was boring having to wait for all of you hp to regen later on when you had 4+, it would be better to have it give your hp back faster the longer you wait.

Something like the first heart takes the normal time to regen, but the next take something like 1/4th of that to regen and so on.

Fun game though!

I found the mechanic to be interesting however movement was a chore. It was slow and then the collision check happened after the movement rather than before. So if you collide with a wall it stops you dead and then you have to stop moving and then try again. Unity has a great collision system, you can even lock rotation so everything always remains aligned. So the movement mechanic was frustrating but the game mechanic was compelling and I could see it be used to very good effect.

Nice Theme Ideas but its just eh, not a puzzle person, not bad but i feel like thats the problem with a lot of devs