Tom Clancy's Rainbow Six Vegas 2 has the best customization features of any game I know of, including role-playing games.
That's one highlight of my newly posted review of the game, which you can read on al.com's Techcetera blog.
I must thank several of my online friends for unknowingly contributing to my review during the course of talking or playing with me: Fortiscule, Fartknockker, TheJoeyMo, StylishFever, Daddy Rocks LV and the cryptically named IC3W01Fcp666 (Ice Wolf). I hope you'll all recognize your particular contribution.
Don't miss the cool stuff about the Barrett M-468 on the second page of the review. It was interesting to me, so I thought you fellows might find it interesting as well.