Firstly congratulations for having the guts to upload a game with terrible graphics but with a lot of the gameplay in it. This is the way things should be!
- When you start, a few seconds of invulnerability (while flashing) would be nice
- When you die, disappear for a couple of seconds rather than instantly reappearing
- Some screens need to be modified so when you enter them from certain directions you do not die
Other than that it has the makings of being a nice enough little game. I wish you luck with finding a willing graphics artist! (If it was me, I'd think about ripping some graphics from other games, particularly for things like the ground)