MGS4

GTA VC

GTA SA

MKII

Genesis 6-Pak

I can't believe hardly anyone has mentioned Tetris; it's easily the most addictive game of all time, so...

Tetris
Chu-Chu Rocket

I don't think I've ever been more addicted to any game more than WWF No Mercy. Customizations were half the fun. Me and my friends or cousins would play backstage royal rumbles. Eliminating one person would take no less than 5 minutes, so doing a 30+ rumble would take hours, but man was it fun.

Honorable metions:

Tekken Tag
Marvel vs Capcom 2
MK Trilogy
any Smash Bros game
and the Mario Party series

Chess
Tetris
Counter-Strike
Elder Scrolls IV: Oblivion
GTA San Andreas
Knight Of The Old Republic Series
Street Fighter 3
Final Fantasy X
Legend of Zelda: Ocarina

I've played through the entire Baldur's Gate PC series more times than I can remember.

I was gonna say Chu Chu Rocket, but then I had to ask myself if I honestly found it addictive, or I just wanted nerd points. It was fun for sure, but I could put it down after a few plays...

since the thread title doesn't specify what type of games, I'm gonna say a cell phone game: Chuzzle. That game is crack. I believe you can play it for free on your computer as well, so look it up if you haven't heard of it.

Call of Duty 4
Burnout Paradise
GTA San Andreas
NBA Live 07
Need for Speed Underground 1/2/Most Wanted/Carbon

Definitely any GTA game. It's such an addicting game that I could play for hours because in GTA, doing nothing is doing something. Whereas in other games, doing nothing is just doing nothing. there is no goal, no collectibles, no boss to defeat, no linear path- just drive around and do whatever the hell you want to. For me, I become so attached because I'm amused very easily. I have unlimited options in the freeroaming environment, and I just get lost in the game.

Diablo 2 did it for me

Pokemon in general.
King of Fighters XI
Team Fortress 2 (current)

Tetris. I play it almost every day.
Dr. Mario. Oh god I love that game so much. I wish I could find my NES and SNES.

Left 4 Dead
Halo 3
GH3
RB2

Tetris
Pac Man CE
Geometry Wars
Pitfall

As a child i used to play Streets of rage and TMNT IV over and over (me and a friend finished TMNT IV 7 times in a day - yeah that game was damn easy). I also played UMK3 and Street Fighter 2 a lot.
As a teenager, Pokemon was probably the game i spent the most of my time with.
The games i find the most addictive in the ps2 are Resident evil 4, MKD, X-Men Legends 2 and Soul Calibur 3.

I tend to play MK4 every day.

I'm pretty much hooked on the Pokemon series.

I've beaten Donkey Kong Country 2 over 1000 times.

I have officially become Super Mario World's bitch.

MK games(all) but leading has to be MKDC, UMK3 then the rest
DKC games
All Star Baseball
Psi-Ops
Burnout 3
Perfect Dark
TMNT:Turtles in Time arcade game
TMNT:The arcade game
Mario games the oldschool ones mainly

Easily Super Smash Bros

Probably Ultimate Mortal Kombat 3. I remember worshipping that game.

I also used to be hooked on Street Fighter 2, and then Parasite Eve later on.

That was all when I little though. Game addiction doesn't happen to me anymore.

1) Mortal kombat 2 (arcade)
2) Zelda 1 & 2 nes
3) Star fox snes
4) Ninja gayden 1
5) Both punch out games
6) mega man 1-5
7) Mario kart wii (online)
8) Ninja turtles games
9) Street fighter 2
10) ESPN extreme games ps1

Various Resident Evils (3 got the most replays in a short time and it's the one I've owned for the least amount of time)

MK11

Dead Cells

Dark Souls

Windjammers

Parappa The Rapper

DOOM '16

MK4

Bitlife game on apknite. Start off a new life in a random character at birth. Your decision will affect your life from birth to death. You will have many half laughing half crying experiences.

Mine favorite is also one of today's most popular games for kids - Minecraft

Them's Fightin' Herds

I want it naow.

1. The Elder Scroll V: Skyrim

2. Doom II (1994)

3. Resident Evil Outbreak

4. Unreal Tournament (1999)

5. Mortal Kombat X