Hmm...
For sheer addictivness- the award goes to Modern Warfare 2.
For most fun and badassery- God of War
For best intro to online gaming but failing to keep me attached because it was the first good multiplayer I had played, or commonly know as the BITOGBFTKMABIWFGMIP- Halo, Combat Evolved (only played the demo, but was addicted) (Was that in 2000 or 1999?)
Best Game- The award goes to - (Soprano's cut off ending)
Edit: just kidding, It definately goes to Oblivion. I barely touch it anymore, but let me tell you, my relationship with that game was not healthy.