1) Playing co-op on Halo 1's campaign. The game is just infinitely fun. It's still, for me, the most replayable Halo title. Second is Halo 3.

2) Having 16 player LAN parties with friends during high school. The laughs, the pizza, the competition, the fellowship. Who needs to go outside to play football when you have Halo?

3) Playing online multiplayer on Halo 1 PC. (Too many hours of my life lost. No regrets). I MISS, so much, the LONG hours of CTF Blood Gulch. Good times. Oh and camping with the flamethrower. The flamethrower was fun, and worked. I miss it.

4) The anticipation of Halo 2, and enjoying the adventure (new trailers, new magazine scans, etc.) with friends. I've never been so hyped for anything in my life. If only Halo 2's campaign was as good as it was advertised. (First play through was fun, but the game is not too replayable for me personally).