Double jumping. Simple really. You contract the muscles in your legs, storing energy. You drive as much force as you can muster down into the ground and while raising your center of mass. You lift off, extending your body into a long smooth crescent. As your ascent slows, you pull your legs back up under you, tucking your knees. At the apex of your jump, you spring out again, releasing every last newton of force. You rise again doubling your previous elevation. Maybe three or four times your standing height. Simple.
Of course the double jump is a physical impossibility. With nothing substantial to act against, pushing your legs out mid jump would be futile. Gravity wins. You could, conceivably, attach some sort of propulsion system to your legs that would facilitate a double jump, but nothing like that exists. Even if it did, it would be far too dangerous to attempt. Double jumps are the domain of video games.
It’s curious that we suspend disbelief for video game characters jumping several times their own height, and then doing it again in mid air. Like portals or bottomless pits, we have no real world analogue to tie it to, yet we accept and understand the mechanics of a double jump with no argument.
There are characters who can fly in other media. Superheroes have flown for half a century. Superhero flying is wish fulfilment, but it’s also not an alien concept in the physical world. Birds fly all the time. No bird ever did a double jump. We have seen examples of crazy wire work in kung fu movies, but as wild as the effect can get the performers are still bound by gravity. Creating a look that is graceful and fantastical, but still plausible is the goal. Movie kung fu does not double jump.
This is the envelope that video games have pushed. Physical absurdity. More to the point, agency over physical absurdity. As soon as you are empowered with directing the feat, double jumping seems perfectly normal. Obvious even. Were you to watch it performed in a movie or tv show, you would find it fake and uncanny. Watching a double jump would distance you from the media you were watching, remind you that this is all just pretend. When you press the button that makes events happen, it feels vital and precise. Tangible.
The real trick then, is not just bending the laws of physics, but applying this tangibility to other concepts. What other abstract or difficult notions can be made real for people through interaction. Can complex math be demonstrated easily by allowing you to interact. Can ways of seeing the world, unconventional points of view, even empathy, be imparted to a player just by pressing buttons. There is no basis historically, culturally, or evolutionarily for a human being to gain an intuitive understanding of double jumping in seconds. To me, that says that teaching anything through video games is possible.