You need gzdoom for this. I'm going to probably make the sequel in zdoom level editor. But I might stay in my comfort zone with doom builder.
An experiment went wrong in the advanced research facility. The systems are offline turn on the power, oxygen, and security, systems and send a transmission to the U.A.C. A.C.C. (Aftermath clean up crew) Kill all three hell brains. One in hydroponics another in the advanced research HQ and another in hell.