linux compatible: 

www.crazymonkeygames.com

www.jigzone.com

yahoo (java)

www.flashflashrevolution.com/FFR_the_Game.php

-----------------------------------
not: 

www.popcap.com 
www.shockwave.com  

zuma (original 3d)

=====================================================
Xonix (like Qix) 
https://dosgames.com/game/super-xonix/

Entrap 
https://dosgames.com/game/moraffs-entrap/

UFO Invasion (like Space Invaders) 
https://dosgames.com/game/ufo-invasion/

Astrofire (like Asteroids) 
https://dosgames.com/game/astrofire/

Zuma -- http://www.popcap.com/games/free/zuma
http://www.freegames4all.net/play-22891-Zuma_Deluxe_Game.html (non-3D,linux comptbl) 

http://www.webpacman.com/pacmanxonix.html

FLTron -- http://www.ebaumsworld.com/games/play/16096/

Alien Invasion 2 -- www.armorgames.com/games/alieninvasion2.html

Starball (like Breakout) -- http://www.agame.com/game/starball.html

http://www.freearcade.com/Xonix3D.flash/Xonix3D.html

Nudge -- http://www.crazymonkeygames.com/Nudge.html 

http://www.crazymonkeygames.com/Curveball.html  (linux comptbl) 

http://www.crazymonkeygames.com/Cosmic-Crush.html

http://www.crazymonkeygames.com/Mars.html  (linux comptbl) 

http://www.crazymonkeygames.com/Nimian-Flyer-Legends.html

http://www.addictinggames.com/rollrollroll.html

http://www.y8.com/games/metal_sphere_solid

http://www.y8.com/games/run_1

http://minishockwave.com/shockwave-games/11/Hypaball.html

http://www.playedonline.com/game/599287/isoball-3.html

feeding Cthulhu -- http://unclecthulhu.com/feeding/index.html

plants vs. zombies -- http://www.popcap.com/games/free/pvz/?mid=pvz_macweb_en_full

http://www.zombiegames.net/games/Zombie-Kittens.html

http://www.freegames4all.net/play-21958-Behind_Enemy_Lines.html

http://www.freearcade.com/AlienSOS.flash/AlienSOS.html?s=new

http://www.y8.com/games/star_wars_trench_run

http://www.crazymonkeygames.com/Darkbase-3.html

http://www.candystand.com/play/the-space-game

The Great Gatsby For NES -- http://greatgatsbygame.com/

All Hallow's Eve -- http://www.newgrounds.com/portal/view/199440

The Last Airbender: Elemental Battles -- http://www.addictinggames.com/elemental-battles-game.html

http://www.y8.com/games/virtual_3d_city  (automated flyover) 

http://www.freearcade.com/RadicalAces.jav/RadicalAces.html

http://www.freearcade.com/Wings1915.shock/Wings1915.html

http://www.y8.com/games/ultimate_motorcycles  (like tron) 

http://www.freearcade.com/3DCarRacing.flash/3DCarRacing.html

http://littlealchemy.com/

http://kingdomofkroz.com

http://www.physicsgames.com/featured-games_angry-birds-online/

http://www.freearcade.com/ReturntoTHK58.flash/ReturntoTHK58.html

http://www.freearcade.com/LibraryEscape.flash/LibraryEscape.html

http://www.freearcade.com/DrPhlogistonSavestheEarth.jav/DrPhlogistonSavestheEarth.html

Candystand Mah Jong (no time limit) -- http://www.candystand.com/play/mah-jongg

http://www.mahjonggames4all.com/game.php?spel=Mahjong+Dark+Dimensions&game=63

Text Twist -- http://get.games.yahoo.com/proddesc?gamekey=texttwist (mac needs safari or seamonkey)
http://www.shockwave.com/gamelanding/texttwist.jsp  (ads) 

crossword -- http://puzzles.usatoday.com/  (linux comptbl) 

Puzzle Baron's Cryptograms (Java) (has ads with sound) -- http://www.cryptograms.org/play.php

==================================

PlaneShift
www.planeshift.it

Runescape  (free levels) 
www.runescape.com 

TruthScape.com
http://www.truthscape.com/

Colony Wars (free, browser-based)
http://www.colony-wars.com/

Forsaken World  (free levels) 
http://fw.perfectworld.com

Second Life

World of Warcraft

Eldritch Errors  (ARG) 
http://eldritcherrors.com/

HabitRPG
https://habitrpg.com/static/front