I liked the game. It reminded me of Commander Keen and maybe the original Duke Nukem. It was fun to play, but my biggest gripe and one that almost had me review this game with me not beating it and give it a lower score was that there is no invincibility once you are touched. Now this normally does not hinder you through out the game until you come to the lava or toxic waste pits where if you fall because of your own error or was hit into it you are as good as dead unless you are lucky. You just keep jumping up from touching it until you are dead mostly.
Secondly, not really sure what to think of the speed dash... doesn't really fit in the game although I have to admit it does help with the long distances. Finally though, what is up with jumping on top of people's heads!?! This is not Super Mario Brothers. I know other games do it too, but it just sort of felt out of place in a shooting game.
And the enemies almost always get the first hit off of you, but I see you tried to work around that by giving an over abundance of hearts, some times I would leave the room with three hearts untouched.
All in all I felt the length was decent for a NG game. I found the pixels charming and the music adequate. Again the no invulnerability when you are injured is a real pain, but I beat it on easy and if you take your time and you have a little patience you can get through. I like the fact that you start back at the last room you were in when you died opposed to the beginning of the level. Not too sure about playing on hard. I did not feel the need to push my self at the moment but I did notice my power ups were taken away but I had a charge gun from the start. I am assuming the enemies take more hits but since I do not remember how the game played on easy when I first started out I can not say. But the enemies still only take one heart from you every time you are hit. I have to say I liked it and would recommend this for a play run, maybe only once, but still a recommendation. Good job.