Can you guys recommend me some gameplay mods?

[TheSlipgateStudios]

For original and BFG Edition, I'm hungry for more!

[Metal_Slayer]

This one is the only one I can enjoy: 

There are many others that break the gameplay loop entirely, if you want to play them, there's also the VR mod.

[Tetzlaff]

Fragging Free combines Doom 3 with more arcade-like, frantic gameplay. Comes with it's own campaign, many new monsters, some new weapons, special abilities and so on. Can also be played with the normal camapiagn and RoE.