its been a while since ive played halo 2, these may be a little wrong
run up to wall and look down and enemy cant see you because your head is in wall
double tap Y when the mag gets put in the gun to reload faster (this also works in halo ce)
iirc if you cloak and then enter a vehicle you still have cloak
if you make an elite outside hotel zanzibar mad you can kill him for energy sword
at the very beginning of outskirts you can jump on a light up to the roof and then grenade jump up and you can jump across rooftops to skip the a chunk of the level
sniper jackals dont have perfect accuracy, i dodged a few shots one time
its best to attack the sniper jackals either before/right when they see you or after theyve shot twice
on the original xbox version you can go through walls if you hump a box around 8 times (you should see the camera jump a little each time if you did it right)
in that snowy arbiter level near the end with flood everywhere you can wiggle the ghost into that burnt wreckage area
throw grenade when you punch regret
i think sometimes the flood get stuck in the pits they spawn in
when elites (including ones with swords) try to melee you, you can dodge it and backsmack them but iirc their melee hitbox is kinda janky and big
edit: also if you mag dump a carbine into tartarus it drops his shields
its been a while since ive played halo 2, these may be a little wrong
edit: also if you mag dump a carbine into tartarus it drops his shields