Super Smash REX is a heavy modification of Super Smash Bros Brawl. Today its team revealed a new trailer that adds a lot of stuff into their mod. Master Chief is the BIG reveal, and he looks great, with fully custom animation and a wholly unique moveset. He even has a bunch of great alternate skins! If you want to see him yourself, skip to about 10:10 https://www.youtube.com/watch?v=0sEO-vzyUaQ

He looks like a lot of fun, and so much of his toolkit is represented, including his Halo 5 thrusters which make for a much more interesting air-game than you would normally expect out of a 7 foot walking tank. Maybe one day we'll see MC in an official Smash game, but frankly, this is already an amazing effort and scratches that itch just as well.