halo on halo is still doable, it just requires management on party leaders part. Basically your gametype is going to change to slayer and you put one guy on the attacking team and every one else on the defending team. On the map you use a player trait zone to make it so the runners cannot harm the "zombie" and set up the weapons as spawns in the center of the map. This allows basically the same thing except the slayer gametype will have to be only one round and you will have to vote or pick at random the next shooter. As for ice cream man its really about player trait zones and teleporters. your gametype is still flood as you can still drive vehicles as a flood and the teleporter leads to a platform with a player trait zone that allows instakill of the zombie. you leave a ranged weaponof your choice up there and the game still works. to be honest this actually works better than the original setup due to the fact that zombie cannot steal the "ice cream". I mean I really hope I'm helping here because I dont want to see custom games die in halo 4 so I'm trying to find alternate solutions to these catches. On the bright side predator is the same as h3...
and as for the other modes did anyone think to reverse the roles of humans and flood?... lol that one actualy just came to me right now ehehehe....