I bought an original Xbox to play Fable, and that was it really. I knew of Halo, but it was like maybe the 5th or 6th game I picked up (on sale actually since it was late in Xbox original's life).
I enjoy Halo to some extent, but it is not the only reason to own an Xbox ... far from it. Xbox original had lots of great exclusives ... Fable, KOTR 1 and 2, Morrowind, Doom 3, Thief, Deus Ex, ect. Besides, I already had a great online multiplayer shooter in the form of Counterstrike ... so did not see value in Halo at all really.
Both Xbox original and 360 made online console gaming a thing, created achievements, ect.
Halo was not really even a selling factor for me. The only Halo game I truly enjoyed and would classify as "great" was Halo Wars which is Halo in name only. Even if Halo never existed, Ensemble could have just called it Gears of War Wars or whatever brand they wanted to attach to it and it would still have been the same great game.
