×
Goes more or less from left to right and from top to bottom

Myst (the space rocket)
The Sims (the green crystal)
Lemmings (the line of green-hairs)
Sam & Max (dog and rabbit)
Bomberman (pretty clear...)
Max Payne (the shooter on a chair)
Duke Nukem (the man at top with glasses)
Grim Fandango (leftmost reaper)
Dungeon Keeper (second reaper)
Final Fantasy VII (spiky hair and the companions)
Army Men (the toy soldier)
Full Throttle (based on memory of seeing that bike before, the man in black nearby seems familiar as well)
Halo (vehicle + armor)
Half Life (man with crowbar)
Leasure Suit Larry (small man with a lot of women)
Monkey Island series (the flaming pirate)
Pacman (on the plate)
Fallout (blue man coming from vault)
Earthworm Jim (the guy with a huge worm as a head)
Worms Blast (seems more like the Puzzle-Bobble kind of worms character rather than the regular Worms characters)
Mega Man (the blue guy in the crowd)
MDK (the sharp-nosed black person in the right-hand edge of the screen)
Discworld (walking chest + wizard)
Warcraft 3 (the bluish royal person)
Rayman (the most cartoonish of the jumping heads)
Doom (the non-mechanical flying and flaming skull)
Doom 3 (the mechanical flying and flaming skull)
Prince of Persia (ugh.. spiketrap)
Diablo (rightmost creature at the table)

× They call me Raging Demon because I'm Jab, Jab, Short, Towards, Feirce.

×Day of the tentacle. (In line)
Planescape: Torment (The skull to the right of rayman.)
Creatures & Creatures 2: Bottom left creature.
American McGee's Alice (Girl with knife on left)
Silent Hill 3 (Pyramid headed guy next to girl)
Serious Sam (Near top)
Bad Dudes (Next to Serious Sam)
Dungeon Keeper (Dominatrix next to Larry)
Solid Snake (Hiding under Bomberman)
Splinter Cell (The beholder (At bottom) Is wearing Sam's gear)
Army men (Video Game) (Being shot near top.)
Laura Croft: Tomb Raider (Right of Larry)
Monkey Island (Guybrush Threepwood) (Top; in tutu)

×monkey island

×Command and conquer (Kane watering tiberium)
Painkiller (guy shooting stake through people)
Evil Genius (blue man in line)
Legend of Kyrandia (Joker in same line)
Knights of the old republic (bald dude with lightsabre, in corner)
Unreal Tournament (guys with red/blue flags)
Did anyone make an adventure game based on the diskworld novel 'The colour of magic'? Because that moving chest with legs seems to be referring to it.
Alien Vs Predator (two monsters in the middle, being held apart)
Hitman (poster with man with barcode)

×Evil Genius: (in the line in front of purple tentacle)

×Abe's Odyssey & Twinsen's Odyssey: centre right, next to Gordon Freeman.

×this picture has twinsen in it.

Also, I dunno if that's Twinsen's Oddysey or technically Relentless.

Man, I miss those games.

×Runaway: guy, girl & briefcase full o' cash in top left
Space Quest: Roger Wilco in bottom left

×Everquest
Noone Lives Forever 2: A Spy in H.A.R.M.S way
(standing behind Larry, left & right respectively)

×BloodRayne: getting shot mid-upper left.
Simon the Sorcerer: bottom left, in front of the Luggage (?)

oh, and the dragonish head sticking out the pile mid-lower left might by Spyro.

×Isn't that the helicopter from Ugh! above the Lemmings? The three people in it would be from something else again though.

×
Carmageddon (the car with a dollar sign above it's head)
Thief (guy dressed in dark blue, stealing the picture)

Is it just me, or does the creature with a shovel look like a zergling with burrowing abilities?

And although I've never played it, that starwars clone seems to be from 'Starwars: Republic Commando' Am I right?

×I think the helicopter creatures look like what google-image says Ugh is.

Not sure I agree with Thief - the guy shouldn't be purple :/

Frogger (?): Under red car
GTA:VC (?): on right, holding tire and getting kicked

×Starcraft: Ghost (cancelled on the right)
Wizardry series (Dark Savant in villain line)
X-Com? (alien holding globe in villain line)
Peach? (left of Larry)
RE 3: Nemesis (Being killed by the guy in front of the body pile on the left)
Commandos? (The men in the pit with Snake)

And yes, the sewage worker's definitely a zerg.

×Doom 2: cyberdemon, arm-wrestling with other monster(who obviously got charred), bottom right corner, at a table.

×Black and White - the huge ape head on the upper left.
Messiah - the "cupid" above the girls.
Vangers - the triangular sign with a crab-like creature on it.
Digger - yes, with a dollar sign above its head.
Lands of Lore - the evil witch Scotia first in villain line to Cthulhu.
Another C&C reference - the elephant with a twin gun on its head (mammoth tank).
Dune - the head of "Earthworm Jim" is the spice worm.
Blade of Darkness - the barbarian with a sword (and a gun?).
Gobliins 2 - buried under the heap of slain creatures near the above.
Baldur's Gate - the guy with a pet hamster on the bottom right.
Another World - The guy hanging in a cage with an alien creature (duh!).
Full Throttle - the bike with the front wheel missing, resting on a crate.
Ecstatica - the cube-headed sword-wielding guy made out of oval polygons.

×
Quake1 (Ranger, rips Shub Niggurath open from inside with his axe)
Quake3 (funny, I thought both guys with flags are from Quake 3 CTF, but it turns out one of them is from Unreal and they're stealing each others' flags. Sarge character and red flag with that cheap skull are unmistakable. I played various Unreal games, but I think their characters are much less distinctive.)

×American Mcgee's Alice - Alice at table with Pyramid Head
(Thief guy is called Garrett btw.)
Resident Evil - Nemesis
Blood - Caleb playing football with zombie head
Star Wars: KOTOR - Darth Malak next to Raziel
(I really want to know who's above them.)
Star Craft - Ya I would think that is a zergling in the manhole feeding the bird...
Matrix - I can't remember the name but it wasn't Path of Neo. Eww.
Mortal Kombat - Scorpion head among all those heads, including Rayman.
Metal Gear Solid - Solid Snake in the trench next to the Commando guys, mentioned.

Out at a limb:
Grand Theft Auto: Vice City - hawaiian shirt? I was thinking River City Ransom but...
Lineage - Dark Elf in lorry.

Ya, Severance: Blade of Darkness, but he has a gun in pic. o_o
And someone else played Messiah. I forgot the name of the game, but I've played it.

× They call me Raging Demon because I'm Jab, Jab, Short, Towards, Feirce.

×Blade Runner - the guy at the computer with the "clon / ne clon" sign