Here is a list of the Cool Linux games (including multi-platform) I have played in the past. You can find all these on PenguSpy.com. As you may have noticed I have included videos of each.
VegaStrike:
www.youtube.com/watch?v=gp0wi4gScdY#t=123
Vendetta Online:
www.youtube.com/watch?v=t65S39lMP80
Warzone 2100:
www.youtube.com/watch?v=sLZiX8blDpE
Xonotic:
www.youtube.com/watch?v=9Zsp1ahGgWE
Serious Sam 3:
www.youtube.com/watch?v=mQGO46QGlbk
True Combat: Close Quarters Battle:
www.youtube.com/watch?v=yvWhyO9IVQQ
Red Eclipse:
www.youtube.com/watch?v=mjHVb3z72tM
True Combat: Elite:
www.youtube.com/watch?v=llSxTYCOs9M
Wolfenstein: Enemy Territory:
www.youtube.com/watch?v=KXGUpaJIy6g
AssaultCube:
www.youtube.com/watch?v=sna52nYCfMg
Amnesia: The Dark Descent:
www.youtube.com/watch?v=4kpctbHXstg
www.youtube.com/watch?v=IXuIZstyM7E
Penumbra: Black Plague:
www.youtube.com/watch?v=At-w8G6YvKo
Cube 2: Sauerbraten:
www.youtube.com/watch?v=W5p9Dt-tMWE
Unreal Tournament 2004:
www.youtube.com/watch?v=DEg_JtnEJfs
Nexuiz:
www.youtube.com/watch?v=me3KeOj4MHY
Enemy Territory: Quake Wars:
www.youtube.com/watch?v=AKmu5RYeEYo
Spiral Knights:
www.youtube.com/watch?v=P7OQRA2kDyE
X-Plane:
www.youtube.com/watch?v=p8rcpa5tQkc
FlightGear:
www.youtube.com/watch?v=IppA2EViIGI
Minecraft ^_^:
www.youtube.com/watch?v=MmB9b5njVbA
Powermanga:
www.youtube.com/watch?v=3DSeqvfmuOc
Scorched 3d:
www.youtube.com/watch?v=ldfZxkPKwdA
ToriBash:
www.youtube.com/watch?v=lzjl0Cu9HgM
Machinarium:
www.youtube.com/watch?v=uwZBdWRSBRs
Jack Keane / Jack Keane 2:
www.youtube.com/watch?v=ipkl3YI3BGo
Shadowgrounds Survivor:
www.youtube.com/watch?v=V3gDcb4QUks
Trine/Trine 2:
www.youtube.com/watch?v=cRe7sYWrNNo
Secret Maryo Chronicles:
www.youtube.com/watch?v=mTv9EnPq7YU
World of Goo:
www.youtube.com/watch?v=fvySATGlMV0
Speed Dreams:
www.youtube.com/watch?v=Wd4Kmu--PYA
OpenMW:
www.youtube.com/watch?v=swXDXgYUqFA
Neverwinter Nights:
www.youtube.com/watch?v=swBhUJY0N5g
CRRCsim:
www.youtube.com/watch?v=097HgunA3Wk
Oil Rush:
www.youtube.com/watch?v=jlkEqrvQ19c
UFO Alien Invasion:
www.youtube.com/watch?v=7gUNeHMiQPY
MegaGlest:
www.youtube.com/watch?v=5tiQH7UV-5Y
0 A.D.
www.youtube.com/watch?v=I_xDEJrf6q4
OpenTTD:
www.youtube.com/watch?v=tsv8VQo3P8c