HALO is one FPS that really did introduce many new gameplay elements. It offers all that is said below and the modifications already in development look to refine and improve the "HALO experience" even more!
This is for Windows XP. These were not made by me. BONUS: I put the Halo- slash- Bungie.net theme for Firefox in the file too! It's labeled bunjie-1. Just open Firefox, open the themes window, then drag it in, apply it, then restart Firefox! These themes are awesome!