This Build engine game might just be my favorite of the good ones (Duke, Blood, Shadow Warrior). It has old school non linear levels with new school game design techniques to help guide the player. There's a lot of fun to be had exploring the very intricate levels. Even though they are complex, you still don't really get lost in them. The weapons are excellent, especially the chaingun. My only gripe is with enemy design. The cultists are a little bland (especially compared to Blood's) and there are some smaller enemies that are plain unfun to deal with.
