After Samus's mission on ZDR, she investigates a dimensional anomaly, and gets pulled into a parallel universe, where Earth is being invaded by Hell, and after crash landing, and some demon fighting, meets up with the Doom Slayer. They will work together, to slay the demons, to rip and tear until it is done. After it's done? That's where the REAL fun will begin.
Part 1 of the METROID: DOOM trilogy. A hostage crisis at the BSL station orbiting Mars calls for the tactics of the Marine Corps' Space Marine Regiment; But their troubles don't end there. A dormant infection of an unknown life form wreaks havoc on the BSL and its surface facility, Olduvai. (Elements taken from Metroid Fusion and the Doom movie. Reviews encouraged)