Game Design: Platformer

I've had this idea for a platform game for a while: basically something like Super Mario Bros., but the key feature would be some kind of change of speed button.  You hold the button, and your character moves at double speed or half speed (or perhaps have a button for each).  Not just walking/running speed, but jump speed, falling speed; all movement would be affected.  And then there'd probably be a double jump feature, or maybe even triple jump, so that a designer interested in making some really complex and challenging levels could have some fun.  What could this change of speed feature add?



I can see a lot of challenges involving projectiles.  Maybe you have to go slow to "float" over projectiles, go fast to fall between them and touch the ground to jump again, and then go slow again to float over another projectile.  Maybe there are horizontal lasers that go across the screen, and the only way to avoid them all is with strategic jumps and good use of slow down and speed up.  Jump to avoid a laser on the ground, but slow down to keep your upward momentum without hitting a laser above, then speed up when it goes away and rise faster to dodge something else.  You could have to jump a large canyon, so large that you have to jump the full distance possible to clear it, and maybe there are vertical lasers spread throughout the gap.  Because you have to hold forwards to clear the jump, the only way to dodge the lasers will be by altering your speed.  You could have moving platform tricks as well.  Have a platform that falls off the screen, and the only way to land on it will be to fast fall.  Then design the area in such a way that a jump off the platform is required.

You could have simple challenges too.  Go slow to float over a single long lasting laser.  Speed to make it past stompers.  Maybe have a level with something coming from behind so you have to speed through the whole level.

I see a lot of potential for this idea, but unfortunately, I don't know of a good way to make it myself.  I'd love to see this game created though, so I think it'd be cool to see anyone make this game.  If someone's interested, I'm sure I could come up with more level ideas for a game like this.