Anyone else played Call of Duty on PC? One of the few games I have ever completed without any form of cheating/getting bored and coming back months later.
It's easy. Even on the hardest difficulty setting, its fairly easy to outwit your opponents.
However, it has an amazing online multiplayer IMHO. I have played it for soo long, and the only reason I'm not playing it now is because UT2004 has distracted me.
Speaking of UT2004, even on the easiest mode I find the Mothership Assualt and Clanlord 1v1 on the single player very hard. Though I would put that at least partly down to AI levels I.E. the Clanlord is insanely good, while your team members are incredibly stupid, and follow you like sheep on any command with the exception of Search and Destroy
Ocarina of Time is a great game as well, because it takes so long to complete that when you do finish you get quite a sense of acheivment. I'm yet to find a better RPG that doesn't involve levels, although I am free to suggestions.
I would still vote Unreal Tournament 2004 the best game of 2004.