Power Up! The Videogame RPG
The concept for this game is simple. It wants to represent roleplaying in the various worlds of videogames. I don't mean console RPGs, which already have a great many systems created for them. I'm talking about mid-80s platformers and sidescrollers. The games that heavily inspire this project are things like Super Mario Bros., Sonic the Hedgehog, Metroid, Megaman, Contra, Castlevania, and (for a twist) Legend of Zelda (both 1 and 2).
That is the idea we're dealing with. That is where this is headed.
The plan so far
Well, what I've noticed is that Sonic and Mario both have a similar hit point scheme: They die in one hit, but have power ups that provide a damage buffer. Mario loses his Super Mushroom and shrinks, while Sonic loses his rings.
My plan is to have the physics involve people having only one hit point to start with, but being able to support themselves with power ups that they lose if they're hit. Guys like the Contra commandos don't have that, and die in one shot, but they get power ups all the time.
For jumping puzzles, I was thinking of providing an Agility stat that would act as both defense roll bonus and a bonus to platforming puzzles, though the PCs would still have to figure out where to place their jumps. There'd also be a trait to let them have double jumps, providing a second Agility roll for platforming and dodging.
It's all formulating in my head, but I should really put it down somewhere visible.
Jumping Puzzles
My most recent experimentation with the problem of Jumping Puzzles has been to use Otherkind dice.
For example:
Jumping Puzzle is:
Dangerous: -3
Devious: -1
Long: -4
But the hero trying to get past it is:
Tough: +2
Clever: +3
Enduring: +2
Comparing them we get: -1, +2, -2
And then the player rolls 3 dice (maybe more if he has an applicable skill, but he assigns 3 dice) to:
Injury
1 = grave injury
2 = serious injury
3 = scratch
4 = uninjured
5 = mussed hair
6 = pristine
Position
1 = clumsy (start the next encounter at a disadvantage)
2 = poor showing (start the next encounter at a disadvantage)
3 = OK
4 = nice
5 = well done (start the next encounter at an advantage)
6 = graceful (start the next encounter at an advantage)
Fatigue
1 = grueling
2 = exhausting
3 = OK
4 = no trouble
5 = easy
6 = breeze
Obviously a system like that gets more at a game like Sands of Time, where you get to survey a room and plan your way through before making the first jump, than it does 2D platform games, but I thought sharing my ideas might be of some help to you.
For Sands of Time you could make a result table for Sand, and putting a low die there would mean you use up sand rewinding and trying again, or Fatigue could be replaced with Sand, not really sure yet.
Platforming
Otherkind? Never heard of it, definitely gonna look into that. I've never seen that mechanic before, so I don't think I get it entirely. Still, that does seem like exactly the sort of thing that should be included. Maybe a variant of that using the stats I've been formulating. Speaking of which, I should post those here.
Otherkind Dice
They're called Otherkind Dice because Otherkind was the first famous game that used this resolution mechanic.
Actually, I remember an older game called Cathayan Arts of Role Play that used the same mechanic.
The dealio is:
You roll a number of dice and after you've rolled them and looked at them, you assign them to a number of categories that represent different aspects of the task.
In Otherkind it was Narration, Motion, Life, and Safety. You roll once and it resolves a whole scene and assign the values to those categories.
In C.A.R.P. it was Attack, Defense, Movement, and Special Moves. You roll once each round and assign the values to those categories.
It works for a Sands of Time game because as a player, I often had to make a choice after an unlucky jump. The blade hit the prince and knocked away half his life. Do I rewind, using up sand but get a chance to do it again without the screwup, or do I just go to the end, and start the next fight with the injury, but full sand.
But I still have another idea I'm researching and tinkering with, so I'm not sure how I'm going to do it yet.

Those games were pretty deadly
Well...
Sonic was alright. Sonic lost his rings, and then had a chance to grab some of them as they fell. But if he got hit even once without any gold rings in his pocket, he was toast. But that was the same case with most villains in those games, one hit, and done.
Will you use some sort of timing mechanism in your game? An actual timer, perhaps?
Some of these games had jumping puzzles in them. If you can come up with an exciting and fun way to resolve PCs getting through jumping puzzles, you may revolutionize RPGs.
Bosses seem to me to be the closest thing to actual RPG style conflicts.