There was a REALLY good map and gametype that did something similar on Halo 3. It wasnt exactly what your describing though. 8 people could play but it was pretty much always 1v1. Every 30 seconds a staircase would spawn to allow the winner of each one on one to progress to the next area. It was called tournament and it was a lot of fun. Great way to get good with the BR aswell. There was more to it than just flat geography which I think made it a little more interesting. You should really check it out because it would be a good basepoint to build ultra MLG off of.
I would love to play the ultra MLG thing your describing but the idea of playing Reach (and actually trying) sickens me. If Znite plays say hi to him for me. Alternatively just do a custom using that tournament map on Halo 3!