No problems.
1The hit box of the bottom pipes seems to be just a little bit too large. It is very difficult to judge when to jump correctly consistently, but this can also be part of the challenge.
2 The top pipes aren't very challenging you can start your slide very early and still make it. Maybe if you had a shorter invulnerability period then it would be more challenging.
3Maybe different difficulties with an increase in speed.
4The sound when mega man jumps seems to be a little too loud if people start playing this game for a long period of time that might become annoying.
5The pipes texture does not seem to match the background or like megaman stage or world? not sure if you know what I mean?
6Maybe bring the background picture down a bit maybe till it only reaches the top pipes barely
7Maybe Unlockables different megaman skins, stage music or worlds if you reach a certain number e.g 1000 megaman classic skin or 10000 another world.
But it's a great game just like it is!
Good work!
P.S this is just me but it would be awesome if mega man when he dies does that old explosion from the earlier games. That's just me though.
But again fun game!