are you sure you are not talking about Halo 1
oh dear, so they included boring "copy paste" underground section again....
well i dont' own an x-box, but i wasn't impressed playing halo 1 on PC. first few leveles are awesome, but later it get's boring and repetitive. i guess it was a break for games consol owners, because there weren't many such 3d Games available there before Halo.
But on PC it's just another 3d shooter - with a story (OMG, OMG!!). i liked Half life much more simply because of rich environment. Not to mention some other 3D shooters before that, such as the legendary Duke nukem 3D, Doom or a couple of RPG's (such as Ultima Underworld 1 &2). Then there were Return to castle Wolfenstein, Medal of honour...
I would choose Morrowind over Halo anytime :P