I'll get started by saying it should be similar to H2, be at least 12 v 12, new larger maps, make it flow better by adding aim assist and larger hit boxes, take away the pistol's power, add new weapons, make vehicles that respect gravity and don't float (unless they are meant to i.e. ghoust, but not a warthog), add button combos, out of map exploration, super bounces, sword flying, butter flying, how jumping, allow modding in custom games, no private chat (teams must talk to each other), add quick reloads, and make jumping the same as halo2 plus etc.