Let's complete that list.
Koios said:
Tharwen said:
Space invaders (Space invaders)
Duck (Duck Hunt)
Max (Sam and max)
Agent 47 (Hitman)
The Annoying Sprite from Okami
Duck (Duck Hunt)
Manny Calavera (Grim Fandango)
Phoenix Wright (Ace Attorney)
Barrel (Donkey Kong)
earthworm jim
Sly Cooper
Gordon Freeman (Half-Life)
Koopa, Squid, Carniverous plant thing (Mario)
Ratchet (Ratchet and Clank) yes indeed it is
arthur of ghouls n ghosts
Bomberman
Haggar of final fight
The Dog (Duck Hunt)
Is that Deadpool? yes (MvC3)
Bubble or Bobble from Bubble Bobble
Probably Samus spin attack (Metroid)
Turret (Portal)
Poison Castle Crasher
Zubat (Pokemon Gold/Silver)
Mr Mosquito
Spiderman
Kirby
Boo, Mushroom (Mario again)
Ivy's Chain thingy (Soul Calibur 4)
Elena's arm (Street Fighter 3 Third Strike)
Scorpion's chain attack thingy (Mortal Kombat) could also be the Hookshot (Zelda)
Spaceships (Starfox & f-zero)
Slime (Dragon Quest)
Megaman
The robotstretch arm is still baffling me, though there's probably lots of options.
Dr Robotnik (my main guess)
Brocken from World Heroes (obscure, but could be true since there's all kinds of fighting game 'limbs' sticking out of her head, he's got white gauntlets though)
Inspector Gadget (there's gotta be a game with him in it out there)
The thing I'm also wondering about is whether the background denotes anything.
PN-03? Rez?
Captcha:
nithic acts.