I'm making a Mega Man improvement. Sort of. I didn't start with that idea in mind, I started with a platformer exploiting cellular automata - instead of generic tile collision, having a variety of materials with different physical properties that make level design really fun(think Boulder Dash, the Lode Runner series, or Falling Sand for the kind of inspiration here - perhaps the single closest game is Jetpack
). Then I made the main character a robot, and started leeching some pose ideas from the Mega Man sprites... needless to say he'll get some powers and upgrades at some point, it's hard to avoid with a well-developed robot character, it fits into "puzzle design" aspects of the game, and I've fallen in love with the sprite I made anyway.
My jump controls are actually closer to Metroid(releasing anywhere on the upside of arc gives a fall speed equal to releasing at the peak) as I find that allows for less frustrating shot placement. I'm not focused too much on pure platforming or combat, so much as "putting the robot in emergent situations" as a result of the materials interacting with each other. The robot powers can further interact with the materials, making all sorts of possibilities come up.
I'm also toying with what adversaries to give this character. Bosses don't fit into the model of this game, so the entire "robot master" model of Mega Man is out the window. But rescuing people works as a goal. So if I have a named foe it would probably be something like zombies or "grey goo" that threatens the people and has to be cleared as part of the win conditions, as well as more general hazards like rocks, fire, acid, fall damage, etc...
My main doubt about the design I have so far is that the goals might "swallow up" the fun. I'm hoping it'll be good as a sandbox experience as well as a pure puzzler, but I'm not sure if both are possible. Most of my inspirations for this design are pretty puzzle-focused.