Shotgun Frenzy is an Invasion themed WAD for Skulltag and Zandronum by Wad'a'Holic. The latest version is 1.4. In Shotgun Frenzy, players must fight hordes of demons to protect their base. The maps are structured in a linear way, starting from the main base and enveloping in checkpoints located in various enviroments. Players start in their base and can buy various weapons and equipment. They have a certain time to get ready before demons breach the first checkpoint. When the match starts, the players have to enter the teleport to the checkpoint to fight the horde. If the demons overrun the zone, the checkpoint is lost. At this point, an intermission occurs.

After the players are ready, they have to teleport to the next checkpoint. When time runs out, the doors are breached and demons will enter the zone. The players have to fight the demons checkpoint after checkpoint, and keep them from reaching the actual base. When the demons overrun the final zone, the teleport is disabled and players have to defend the core located in the base. If the demons destroy the core, the players lose. If the players defeat the hordes, they win the match, and start a new map. Some maps have special features. One of the players can be the commander, and create buildings in the base. They can build turrets, an armory and genetics labs where players can get special equipment.

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