For me it was Prince of Persia: Sands of Time and Halo.

I was RPG/Strategy games (who sometimes plays adventures), but I never got into any action games. And both those games I run only to check them, and I end up in finishing them both.

I was also surprised by KOTOR, and this is because I enjoyed Baldur's Gate/PST/IWD games so much, then at that time I'd never thought of trying other RPG than isometric. And I really didn't like the way NWN went. So I was a bit surprised I enjoyed KOTOR so much.

For me, now you're gonna laugh and point at me with your fingers, it was Bad Day L.A.

Not sure whether I loved the design or the humour so much, enough to say that this is one of my best remembered games ever :p

Civilization for me. Before this i was more into rpg or shoot em up but when i saw a review on st format how good it was and although the graphics and sound where functional i got swept into the game with ease. Many a time i would just play the fist 1000 years just for the exploration.

Back when I bought my first PC in '98, I was rooting around in the contents and found a DVD that came free with the purchase. 'Baldur's Gate?', I thought to myself, 'Never heard of it but I'll give it a shot.'. How I laugh when I look back on that now, especially considering the other freebie was Lethal Weapon 3. Close call.

That game lit my interest in RPGs, and still gets completed a couple of times every year.

The only other game that really springs to mind in this respect was STALKER, mainly because it had been declared too buggy to play and yet it remains one of the few games I have actually completed.

Planescape: Torment

It was my very first Infinity Engine game and I got my fix... errr copy back then in 2000 (or 2001). And I still have it!

When I started playing I realized that I knew nothing about the Planescape setting although I loved and played AD&D for many years. And the game totally sucked me in and it was full of twists and surprises and I was so excited to find out more an more pieces of information about the world around me and about the protagonist.

Best game ever!

Puzzle Quest: Challenge of the Warlords. I tried it once "just to see how shitty it is". And I've spent many nights with it so far....

Prince of Persia - Sands of Time.

Expected a cheap console port I wouldn't enjoy. Got sucked in by the intuitive interface, atmosphere and the Prince-Farah interactions. One of my favorite games of all time, why my favorite game ending of all time by a longshot. The two sequels didn't measure up.

Painkiller

I knew it got good reviews, but I didn't expect it to have such awesome level design!


Chronicles of Riddick: Escape from Butcher's Bay

Damn, this game could give Half-Life 2 for the single player shooter crown! I certainly didn't expect that!

I have to throw in with Chronicle of Riddick: Escape From Butcher's Bay as well.

The first time I played this game, it was a demo of the first level from another game I'd rented on the XBox. I was blown away. Later, I got the full game as a present on PC, and that just confirmed that this game was truly something special. I was not at all expecting so fantastic, especially seeing as how shitty the movie Chronicles of Riddick was.

That may actually be a first, that a licensed game is actually leaps and bounds better than the movie.

Oh, and Enter the Matrix. I won't even pussy foot around, I actually liked this game and was surprised that I thought they did a great job of the game mechanics, and I've played it through a couple times. Hit the cheat to have unlimited bullet time and it's even better. :D

Hotel Dusk: Room 215 and The Phoenix Wright Series

I didn't realize when I first played these they they were part of the Visual Novel genre. After that I discovered several of what I though were adventure games actually fell in to this category as well and have since gotten more visual novels.

I had the exact same experience, but was especially impressed with the first boss.

Oh
my
god

when the zombie-thing lumbers into view ... and the sound it makes ... damn.

Other: Lost odyssey. I'm not really into JRPGs, but i played it through in one sitting. Well, almost. With sleep/coffee/shower breaks.

Cold War for xbox. I thought it was a splinter cell rip off, and for the most part it was but I actually enjoyed the story, and the gameplay is fun once you get used to the controls. The x-ray camera was a good game mechanic as well.

It also had a MacGyver aspect.

The Longest Journey: I got this when I bought the Game of the Year Edition of Dreamfall. I ended up liking TLJ better than Dreamfall.

Bioshock: I'd never liked first-person shooters before, but this one sucked me in.

Shadow Hearts Covenant: Gave it a try, and loved it. Its a great, underappreciate RPG.

Final Fantasy VIII (and the Final Fantasy series as a whole): I'd never played a Final Fantasy game before, and I had no desire to. FFVIII came on a Playstation demo disk with some other games. I had a friend over to visit (this happened in middle school), and I was showing her all of the other games on the disc that I liked, and on the menu screen, she called out "Oooh! Can we play Final Fantasy VIII? Please?" I (reluctantly) said okay...and...yeah.... Now, everytime a new Final Fantasy comes out, I make sure to remind her that its HER fault that I'm now hooked on these games

Kingdom Hearts: I honestly didn't know what to think when I started this game, but I ended up loving it...and the whole series. (Currently replaying Birth By Sleep!)

BlazBlue - I like 3D fighters like SoulCalibur or Tekken, and I never ever managed to play a 2D fighter properly. Until BlazBlue that is... It's just awesome.

Team Fortress 2 - Back when it was still fresh, my best pal showed it to me on his comp... You know, I wasn't that blown away while I was watching. But then he let me play as a Medic... I can be credit to team while NOT shooting anyone at all!? SOLD! And I've had some awesome experiences playing with others online in TF2.

Bayonetta - I was hyped for the game, I knew it was going to be awesome - but it blown me away completely and more! I'm still playing it (it's a month now of NON-STOP INFINITE CLIMAX) and haven't uncovered all the bonuses. I'm determined to get a Platinum Trophy on this, and I never felt that drive so far. So much fun! NON-STOP INFINITE CLIMAX!

I'm sure there's more, but these come to mind instantly.

For me, I would have to say definately Minecraft. I mean just take a look at a few youtube videos, and you will swear a game designer from 1996 didn't realize the market had passed him by. This game appears to have low res, retro style graphics, no discernible story line, and absolutely no instructions to get you started. Well, a week or two ago, I found out that the game was on a "free weekend" due to a massive server overload, so I figured "meh, I'll try it..." several hours later, my wife is greatly annoyed, and I am trying to defend myself for playing through one more in-game day to finish building my newest extension on my castle. I never expected to get sucked into a game like this, let alone bring myself to actually pay for a game in an alpha stage.

Good call. Definitely concur with this pick.

Also, now that I'm addicted to it, Magic the Gathering : Duels of the Planeswalkers. I downloaded the demo figuring I'd hate it. I've now sunk probably 5 hours in to it, played through the campaign once and a few challenges, and I'm raring to go again.