Here it is, one of the most comprehensive listings of free internet, obtainable games!
MMORPG:
-Fairyland (like Ragnarok): http://www.fairyland.com.my/
-Adventure Quest (try it, requires Flash 6): http://www.battleon.com/
-Priston Tale (Asian RPG): http://www.pristontale.com/
-PlaneShift (very nice graphics): http://www.planeshift.it/
-Dark Eden (now doesn't require a Korean ID): http://www.darkeden.com/en/
-Faldon (small scale MMO): http://www.illusorystudios.com/
-Dransik Classic (may be free, not sure): http://www.dransik.com/classic
-Mu Online (looks like Diablo 2): http://www.muonline.com/
-Build Your Own Net Dream (complicated name for a multiplayer game builder): http://www.byond.com/
-Fung-Wan (or something, it's Chinese): http://fwo.edenii.com/
-Runescape (like UO): http://www.runescape.com/
-Conquer (I think its a MMORPG): http://www.conqueronline.com/
-Space Federation (kind of like Master of Orion): http://www.spacefed.com/
FPS:
-Cube (looks very good, worth a try): http://wouter.fov120.com/cube/
-Wolfenstein Enemy Territory (basically RTCW, free to play online): http://enemy-territory.4players.de:...p=getit&lid=68t
-America's Army (yeah, the one from the Army): http://www.americasarmy.com/
-Hidden and Dangerous (I love this game): http://www.fileshack.com/file.x?fid=3825
-Marathon (redesign of the original): http://source.bungie.org/ The data files are available here: http://orbitalarm.bungie.org/downloads/alephone.html
-Wulfram (tank based shooter, online play): http://www.wulfram.com/
-Blackshades (randomly generated love, Linux and OS/X only): http://wolfire.com/blackshades.html
-Tribes 1 (yes, the full thing): http://www.fileplanet.com/files/140000/140246.shtml
-Tribes 2 (again, the full thing): http://www.fileplanet.com/files/140000/140247.shtml
-Kkrieger (only 96 KB, and has amazing graphics): http://theprodukkt.com/
Puzzle:
-Bontago (addictive puzzle game): http://www.allwest.net/~sanderso/
-DROD (check it out): http://drod.net/
-Chromatron (mirror game): http://silverspaceship.com/chromatron/
-Laser Tank (tank puzzle game!): http://pages.globetrotter.net/lasertank/ltank_en.html
-The Timmy's Picross (remake of the classic): http://www.thetimmys.com/flash/picross/
-MadMaze (old game from Prodigy): http://pages.prodigy.net/rdbrownmsb/MadMaze2/
-Clickomania (remake of old Mac game): http://www.clickomania.ch/click/ (Win/Mac), http://klickety.sourceforge.net/ (Linux)
-Enigma (addictive puzzle game): http://www.nongnu.org/enigma/
Strategy:
-Warring Factions (Goon-made, so you know its good): http://www.war-facts.com/
-Wazzal (single player space privateering game): http://www.monkkonen.net/wazzal.php
-Shattered Galaxy (Real-time, a lot like StarCraft): http://www.shatteredgalaxy.com/
-Pirate Wars II (Goon-made): http://www.piratewars2.com/login_form.php
-Allegiance (GREAT looking spaceship game): http://www.freeallegiance.org/
-Steel Panthers (turn based WW2 game): http://www.matrixgames.com/games/WorldAtWar/main.asp
-Space Merchant (space trading game): http://merchant.shareplay.com/
-Star Kingdoms (similar to Warring Factions): http://www.starkingdoms.com/
-Megamek (BattleTech Board Game): http://megamek.sourceforge.net/
-FreeCiv (Civ 2 clone): http://www.freeciv.org/
-Warpath (Conquer the universe!): http://www.synthetic-reality.com/warpath.htm
Side scroller or Top Down shooter:
-Soldat (cool online play, very worms-esque): http://www.soldat.prv.pl/
-Notrium (single player top-down survival game, like Crimsonland): http://www.monkkonen.net/notrium.php
-Crimsonland (top-down shooter, free to play, but you can "register"): http://crimsonland.reflexive.com/crimsonland/
-FaceWound (Goon-made, so you know its good): http://www.facewound.com/
-GunBound (online play, very addictive): http://www.gunbound.net/
-Survival Project (interesting Asian game): http://english.spgame.com/
-rRootage (fly spaceship!): http://www.asahi-net.or.jp/~cs8k-cyu/windows/rr_e.html
-Grand Theft Auto (yes, it's free now): http://www.rockstargames.com/classics/gta.htm
-Continuum (multi-player Asteroids!): http://www.subspacedownloads.com/?act=file&fid=5
-Warning Forever (I honestly don't know what this game is about): http://www18.big.or.jp/~hikoza/Package/wf102.exe
-Liero ("some sort of ******* child of SOLDAT and Worms"): http://helios.et.put.poznan.pl/~sskowron/liero/
-Scorched Earth (a lot like the classic Bomb): http://www.classicgaming.com/scorch/
-Hot Persuit (like Spy Hunter): http://www.megagames.com/news/html/...aypursuit.shtml
-N (ninja platformer): http://www.harveycartel.org/metanet/downloads.html
-Half-Life: Codename Gordon (the long awaited 2D HL): http://www.pha****er.com/cs/files/codename_gordon.zip
Adventure:
-Kings Quest (there are other games here too): http://www.agdinteractive.com/
-NetHack (single player RPG): http://www.nethack.org/v343/downloads.html
-Angband (similar to NetHack): http://www.thangorodrim.net/
-The Ur-Quan Masters (another space game): http://sc2.sourceforge.net/
-Ancient Domains of Mystery (like NetHack): http://www.adom.de/
-Progress Quest (try it): http://www.progressquest.com/
-Betrayal at Krondor (old school RPG): http://www.the-underdogs.org/game.php******116
-Beneath a Steel Sky (I remember this game, play it!): http://www.scummvm.org/
-Out of Order (in the vein of old school Lucasarts games): http://outoforder.adventuredevelopers.com/
-The New Adventures of Zak McCracken (or something, fan made remake of old Lucasarts game): http://gamershell.com/news_BTheNewA...esofZakMc.shtml
-Dink Smallwood (like Zelda): http://www.rtsoft.com/dink/
-Elder Scrolls: Arena (granddaddy of Morrowwind): http://www.elderscrolls.com/downloa...loads_games.htm
-Graal (Fantasy/old world RPG): http://www.graal2001.com/
Other:
-Tactics Arena (online only tactics game, like Final Fantasy Tactics): http://www.tacticsarena.com
-Hattrick (manage a soccer team): http://www.hattrick.org
-Stepmania (home version of DDR): http://www.stepmania.com/stepmania/
-Darksigns (hacking game): http://www.jqb.netglob.com.pl/darks...staller_091.exe, then patch with this http://www.jqb.netglob.com.pl/darksigns_patch_0.92.exe
-Button Men (online version of a dice game): http://www.buttonmen.dhs.org/
-Babylon 5: I've Found Her (space sim): http://ifh.firstones.com/
-Stair/truck Dismount (great time killer, good physics): http://jet.ro/dismount/
-Orbiter (space flight simulator): http://orbit.m6.net/
-Legends (APPARENTLY its some remake of Tribes 1): http://hosted.tribalwar.com/legends
-Noctis (space picture thing game): http://www.anywherebb.com/
-Pokemon NetBattle (online Pokemon game): http://www.netbattle.net/
-Decker (based on the Matrix from Shadowrun): http://www.caro.net/dsi/decker
-River City Hacky Sack (cool game): http://www.somethingawful.com/rchs/
-Megamek (adaptation of the old Battletech board game): http://megamek.sourceforge.net/idx.php?pg=main
-Starships Unlimited (shareware, but fun): http://www.apezone.com/
-One Must Fall 2097 (old but cool fighter): http://www.omf2097.com/
-Cybots (online bot game, SA already has a clan going): http://tasman-studios.com/cybots-be...&rsm=X982246113
-Silver Knights (3D mech shooter): http://www.megagames.com/news/html/...erknights.shtml
-Tong (Tetris + Pong = Tong): http://www.nongnu.org/tong/
-Vantage Master (engrish RPG): http://www.falcom.co.jp/vantage/index_e.html
-O2Jam (DDRish, I guess?) http://o2jam.e-games.com.my/
Collections:
-Game Tunnel (random collection of games): http://www.gametunnel.com/html/modu...p?name=GT_games
-The Underdogs (where old classics go when they don't sell anymore): http://www.the-underdogs.org/
-PopCap Games (mostly puzzle games): http://www.popcap.com/
-Virtual Apple (old Apple 2 games): http://www.virtualapple.com/
-Megagames (most of which are already posted, but some new ones): http://www.megagames.com/news/html/...freegames.shtml
For all of your text-based gaming needs, go here: http://brasslantern.org/ Games available here: http://baf.wurb.com/if/index
If you are having problems running old games on your new computer, use DosBox.
http://dosbox.sourceforge.net/
Hopefully they all work. And they should keep you busy for a while.
I like playing games online depending on the game I could be on the computer for hours and hours playing a game I love alot. 
