I always liked those platform games that did something extra besides jumping, shooting and collecting. Like pulling up beetroots and throwing at the enemy, flattening enemies by jumping on them, and swimming with the fishes... OK I like Super Mario, who doesn't ?
But as long as the control is perfection, you're safe I think. I think the trick with your engine might be to make the control absolutely perfect but still parameterized so that every platformer made with the engine doesn't feel exactly the same, but is configurable. Good luck!