What are the games on each console that you can't do without, must buy, never sell quality stuff that forms the backbone of any decent collection?

360
Oblivion
Dead Rising
Gears of War
Geometry Wars

PlayStation 2
Okami
God of War
Final Fantasy X
Devil May Cry
Vice City
Disgaea
Katamari
Ratchet & Clank 2 OR 3
Gitaroo Man
Frequency
Zone of the Enders 2
Shadow of the Colossus

Xbox
Burnout 3
Halo
Halo 2
Otogi
Splinter Cell: Chaos Theory
Prince of Persia: Sands of Time
Ninja Gaiden (maybe...)
[more games here that just miss the cut than on any other system]

Gamecube
Wind Waker
Mario Sunshine
Metroid Prime
Resident Evil 4
Paper Mario 2

DS
Mario Kart
Phoenix Wright
Trauma Center
Elite Beat Agents
New Super Mario Bros.

PSP
Lumines
(man MGS: Portable Ops is tempting)