I couldn't possibly go through the list of all the video games I own - I collected retro stuff since before there was really a market for it and it was just outdate junk. People made fun of me for hoarding this stuff and now it's worth a fair bit of money... who's laughing now? But here's a list of systems I currently own:
Atari 2600 x2 (late '70s "VCS" wood veneer model, plus the 1980s reissue)
ZX Spectrum (x4 - each one a different variation)
Amstrad CPC
Commodore 64
Commodore Amiga 500, 500A, 1200
Sega Master System (1x Both versions)
NES (x2)
Sega Megadrive (Model 1, Model 2 x3)
Original Gameboy
SNES (x3)
Sega Saturn x2
Playstation (x4 - 2 of the early big ones, two "PSone" mini ones)
N64
Sega Dreamcast
PS2
Gameboy Advance
SNK Neo Geo Pocket (I actually have no games for this - not one. Never found any!)
Gamecube
Xbox
Wii
Xbox 360
Lots of games for each of them, I have them all organised in various boxes but I'd have to get them all out and look through them to find out what I have, and that would take days!
Also I have PCs but I don't really use them for games. My desktop PC is too outdated and my laptop isn't really optimised for gaming so... yeah.
Somewhere, I also have a couple of Nintendo Game and Watch units - these actually served as my alarm clock throughout my high school years (2001-2006) because I was so cool back then, nobody even knew it yet