Then the seams of reality began to fray.

NSwTcH-NSP-Actualiza_Doom_2016_v2.0.corrupt

From the ventilation shafts, a smell: ozone and burnt marrow. The floor tiles softened, turning porous, like Martian rock. A low, rhythmic thumping began—not machinery, but a heartbeat. The UAC’s heartbeat. From DOOM 2016 .