-Charger physic client side manipulation (turning and infinite charge + teleportation)
-Hunter infinite air jump
-Instant healing / teammate pickup / reloading / never failing from cornice
Others
Invisible jockey
Damage immunity to smoker
Jockey and charger exploit to crash servers
I know this game is a lost cause but come on, i can't believe that nobody tried to decompile one of these programs to understand how these exploits work.