no order
chaos engine - amiga (hd remake plz!)
quake3 - still mapping for this
doom - still great after all these years
warcraft3 - yup, rts gold
diablo 2 - best coop ever
company of heroes - been playing everyday for months. great coop again
hired guns - another great coop game on the amiga
gran turismo series - cant pick 1
wolfenstine et - best team based shooter of all time! loved playing medic and engy
ff7 - the only real master piece from the series imo
honorable mentions: system shock 2, skies of arcadia, capcom vs snk, soul caliber series, moonstone... the list just goes on and on