I think that the majority of first-person shooters would be greatly improved if they simply let themselves sloooowww doooowwwn. Seriously. The first person angle can be extremely immersive, if one's allowed to focus on more than shooting and not being shot. Exploring your typical FPS's corridors is much more intense when it's eerily silent, rather than echoing with gunfire. Add in a few encounters with individual enemies here and there, and the tension in the level would be almost unbearable. Also, with fewer bullets flying through the air, you can crank up the bullet damage/realism. Intense stuff. Sure, a firefight every now and then at key places is great, but many games have simply become a constant firefight (*cough* Black Ops *cough*), which becomes tedious rather than the adrenaline-filled fun that it's supposed to be.