I’ve included the system on which I had the best experience with the game
1. Metal Gear Solid 3: Snake Eater (ps2) The creativity by the writers and conceptual development is top-notch. Playing through this is an invigorating, emotional, inspiring experience.
2. Mass Effect (pc) I’ve never been so involved in the story of a game in my life.
3. Shadow of the Colossus (ps2) This game has an incredibly unique concept, and a special atmosphere. It’s quiet, vague, subtle, and filled with beauty.
4. Half-Life 2 (pc) I think this (along with Half-Life 1) is the most ahead-of-its-time game – even considering Mario 64, Zelda, and Doom. The physics engine and puzzle design along with the first person story-telling was revolutionary.
5. Silent Hill 4: The Room (ps2) So scary it’s cruel. I never saw horror the same.
6. Mirror’s Edge (ps3) This game is visually stunning, the score is great, and the movement and character control feels very energetic and natural. This game really makes me feel like I am this person. And this game is really designer friendly :P
7. Metal Gear Solid 4: Guns of the Patriots (ps3) Another Metal Gear game captures most of the same magic from 3, and even takes some aspects way further – like the cinematics.
8. Indigo Prophecy (ps2) What an exciting game! This game captures suspense very nicely. And its story and characters are well-developed.
9. Hitman 2: Silent Assassin (ps2) None of the other games in the franchise were quite able to capture what this one had, I’m not sure I can be more specific than that. It was just special. There was something really disturbing about this game… something I can’t explain.
10. *Grand Theft Auto: Vice City (ps2) The 80s culture makes this gameplay kind of campy and extremely fun. And this is my favorite radio selection of the franchise!
11. Brothers in Arms: Earned in Blood (pc) This wasn’t just a shooter. It’s very realistic. It really felt like World War II. You care about the people you fight with. When they get shot, you scream, no!!! It was a different shooting experience.
12. *Silent Hill: Shattered Memories (ps2) It’s a stroll through the disturbing. Without combat, the game is allowed to focus on the defining features of the series.
13. Spider-Man 2 (ps2) Free-roam web-slinging all around NY? Yes, please.
14. Freedom Fighters (ps2) So, so, so fun. I beat it probably ten times. Always wanted a sequel.
15. Portal (360) A fine exercise in technical experimentation.
16. Fighting Force (ps1) I used to not own a memory card, so in the late 90s when my brother and I played it, we would have to beat it in one sitting. It was pretty hard, we only did it like twice. Good memories.
17. Twisted Metal 2 (ps1) Just a classic for me. Another good 90s game.
18. Oblivion (360) Fantasy environment and role-playing I can’t imagine being done better.
19. Mercenaries (ps2) I just loved how you can accomplish your mission in so many different ways. And I loved capturing the deck of bad guys.
20. Far Cry 2 (ps3) Free-roam in Africa? Oh, heck yes. Not to mention the amazing “sun shining through the jungle plants” engine.
* represents REVISIONS made since first publishing the post.