Breakdown - the ending, and deciding that you can go to a different dimension, and save that one...so bad ass.
FF7 - Lucky 7's on Emerald Weapon...I almost died., so hype
Guilty Gear Midnight Carnival - Beating Gold Sol in M.O.M.
Zone of the Enders 2 - Fighting Vic Viper....only to find out its piloted by the GOAT, Leo. Fighting Anubis.
ME 1 - Making Saren shoot himself.
Breath of Fire 4, the "bad" ending.
Legacy of Kain; Blood Omen; The canon ending.