Image 4 - Xim's Helper Marines mod for Doom

This mod is an ally pack that includes Doom marines of each weapon, plus a few extras. Allies start with the player and follow them through the map. You can set any combination of marines you'd like in the menu. There is also a 'progressive' mode, where helpers are unlocked for the next map by finding items or completing the map with a certain amount of health or ammo.