Years ago had someone mentioned the word "Halo" to a teenager/young adult most would have immediately thought of the symbol of divinity. However that has changed drastically now, chances are that if you ask them now most would immediately think of Bungie's masterpiece. The series now has three main games(including this), a RTS spin-off based 20 years before, and an entire series of books.
General: Halo is without a doubt one of the greatest games on Xbox and probably saved the console from having the same fate as Sega's Dreamcast. This FPS(first person shooter) has a story which is riveting and non-stop action.
Single-player(non-online): The single-player campaign is fantastic with and offering of ten missions, each lasting roughly 10-40 minutes. The player takes over Spartan 117 of the elite SPARTAN program and fights the alien threat known as "The Covenent". The missions are all extremely engrossing, with enough twists and a fantastic story to add to it. Add in the ability to choose between the difficulties and solid co-op play and Halo has one of the best single-player experiences available on the Xbox. The one thing that keeps this from obtaining a perfect score is the slight clunkiness of co-op because it doesnt make sense having two spartans.(Good luck beating it on legendary!)
Multi-player(couch and online): Easily the best multi-player available on the Xbox when it was released. It allows for four player split-screen and system-linking to other Xboxs for 16 player play. However it can connect over the internet using unofficial services like XBConnect which allow for large games over the internet(however some can be extraordinarily laggy). Halo features Team Slayer(much like a team deathmatch), Slayer(classic free-for-all), Capture the Flag, several others, and an option to create your own game-type which leads to tons of fun with friends. Halo complements the gametypes with 13 maps all of which feature different and interesting builds.
Replayability: Halo's replayability is almost unprecedented for when the game was released and the the system it was on. The multi-player adds hundreds of hours to the amount of time one can play and pulling an all-nighter with a friend attempting to beat every mission on legendary is an experience all in its own.
Sound: Halo's music is imaginiative and one of the best of any videogame. Composed by Martin O'Donnel the music has a variety of roots mixed in a fantastic fashion. It sets the tone for a fantastic adventure, intense battles, and suspense. There is nothing much more pleasing then driving through clear territory in a warthog(Halo's equivelent of a beefed up military hummer) then Halo's battle music begins playing and you drive right into a covenant armada.However the normal sound-effects don't live up to the standard set by the music and is best described as average which is why this category didn't get a perfect score.
Graphics: Halo's graphics are fantastic for when it was released and the console it was made on. The abstract pallette used adds to the epic story and complements the fighting. Also the detail put into small aspects of the game like the glow of the plasma weapons and grenade explosions adds to the overall atmosphere.
Overall: A true masterpiece among games and should be played by any fan of the FPS genre.