It was much more unwieldy when i start making the player movement because i wanted realism, but i thought no one would like it, so i changed but i  couldn't do all the changes i wanted due to lack of time.

And yes, i think in invencibility but i left that to the last and time was running out because i needed to fix some errors in the html version of the game.

I'm glad you like it. :)

It's possible, is a known issue.
I use Chrome and works fine.