I made a custom loop movement engine thats remarkably similar to those found in MMF2 games. It features a double jump and not much else, but I figured since the topic hasn't been discussed much and only a basic movement engine has had an example uploaded, I'd upload this. Also would be nice to know if anything can be cleaned up with Construct features I'm unaware of.
You can tweak things by modifying the variables in the red cube, like speed and mount of air jumps and the likes.
(oh right Z to jump, arrows to move)