Not in order, just 10 games everyone should have played at some point:
Beside each game I'm going to put the reason why
1. CoD4 - Best console online multiplayer experience ever
2. Fallout 3 - Just a straight up amazing game. Fallout 3 Broken Steel Add On is easily over 100 hours of gameplay if you explore, do side quests, and replay the game a couple times with different character setups.
3. Super Mario Bros 3 - The best game (my opinion) in the most popular series of all time. Probably the best 2D platformer ever.
4. The Sims - One of the best PC games ever
5. Gran Turismo 3 - The best game in the best racing series of all time
6. Pokemon Red/Blue - Best handheld game of all time
7. No One Lives Forever - An amazing PC/PS2 game but sadly got like no attention. Deserves way more credit.
8. Halo CE - Best Xbox game ever, one of the best FPS game ever
9. Crash Bandicoot 3: Warped - My favourite platformer ever. Better than Mario in my opinion. Too bad this series is a joke now.
10. Any Grand Theft Auto game between GTA3 and San Andreas - Best sandbox games ever and a must play for anyone! The 2D ones on the PS1 were fun too but the 3D ones are amazing.