* Destructible environment. Area effect weapons can destroy walls. Gives a nice, powerful feeling when done.
* Explosive barrels that explode if hit. Can also be pushed around. Creates some interesting strategies.
* If you move forward straight at a monster having a distance weapon you have a much higher chance of getting hit than if you zigzag when going forward against it.
* Weapon: Gatling gun type weapon that does not do much damage while the weapons warm up but after several turns of consecutive firing do a lot. Uses a lot ammo.
* Weapon: Flamer. Creates a moveable wall of flame. Differs from a ray by persisting until cancelled and creating an a fire obstacle also during monster movement.
* Weapon: Shotgun. Damage in a cone shaped area that decrease with distance. High knockback chance. Slow reloading that with an upgrade can occur while moving. So what in effect happens is that you try to get close, fires a shot that kills or knocks the monsters back, you move forward again (and reloads automatically), knocks the monsters back again... Just like in the movies.

* Complex upgrading of equipment. Somewhat similar to gems but much more complex. Many different upgrade packs can be combined, if you have the necessary skill, into very advanced equipment.
http://doom.chaosforge.org/wiki/Assemblies
* Gore. Lots of blood and corpses when killing things.

