1. Legend of Zelda: Ocarina of Time- Pretty much the most epic game I had played up to that point, and is still enjoyable today, unlike many early 3D games
2. Halo: Rocked the boat after having played stuff like Unreal and Half Life before. Many fond memories of multiplayer
3. Prototype: A temporary addition to my top five, which despite many of its large flaws (such as close quarters combat) it gave the best impression of free movement in any sandbox game I've played, leading to hours of flying about, claws at the ready.
4. Final Fantasy VIII: played this before VII, and ranked it higher seeing as the cartoony graphics of its prequel didn't really do it for me.
5. Soul Calibur: Played this game for effing years. Dominated my Dreamcast collection.
Honourable mentions to Halo 2, F.E.A.R, Prince of Persia, Resident Evil 4 and Half Life 2 series