Here are sample icons of games for you to play with. I do not pretend to own the copyright of them - they belong to their owners. Some are only playable under wine. Right click on the icon to save.

armyopsicon
coldwaricon
doom1icon
doom3icon
enemy-territoryicon
fakk2icon
farcryicon
heretic2icon
mohaaicon
nwnicon
quake1icon
quake2icon
quake2icon
quake3icon
quake4icon
sinicon
soficon
sof2icon
ut2004icon
wolfensteinicon
wolfmpicon
wolfspicon