There is always Halo CE and Warthog Football. The easiest place to set it up is in Silent Cartographer. Just head to a certain location (preferably by the natural archway on the beach), kill some marines until you have a decent stock of grenades dropped, park your warthog on top of the grenades, save after the checkpoint and backup the save (in case you hit another checkpoint).
Now toss a grenade behind or onto the warthog, and see if you can score a field goal with it. Bonus points if you use the warthog to launch yourself as the ball instead (and survive; bonus points for not using an overshield); even more points if both you and the warthog land on the field goal mostly unharmed. It can't be done in Halo 2 or 3 as easily, seeing as they have damage models and no health bars (only shields); and Halo 3 and beyonds' sandbox mode doesn't count.
This really has been more fun to do than playing the actual game. Bullfighting Hunters was also fun as well, along with 1-shotting them with a pistol (HaloCE again).
(Method was originally found by Randall Glass, I believe.)
Link (Found it; the original was 404'd, but this was the same first video I saw of it in action.)
Ahh... memories. Halo 1 and 2 had some awesome bugs. Superman for Halo 2 before it was patched was quite fun to do. Do a Youtube search for 'Dark helmet Halo'. I remember he had some epic ways of playing Halo games wrong.
Actually, anything here is awesome for Halo Breaking Site's in cryo, so don't expect anything really new anymore. I used to visit it regularly during Halo's heyday.
Always was a fan of
Jump Tactics. You can try to do these in any other game, given the opportunity, and hopefully a lack of invisible walls.
