Interconnected and realism themed vanilla-ish level design. Different difficulty setting. Single or co-op 2-4 players. No advanced engine needed. No jumping needed. Falling damage may kill you. Has official OST addon. May crash in some DOS engines like Chocolate Doom or Steam's DOSBox due to large level design areas. Tested and works fine in Crispy Doom and PrBoom+.
Demons are allowed to live on Earth after the portal to Hell was opened by the UAC. Demons shall not kill the living. Demons shall not disturb the living. Demons shall obey nature's will at all times.
You are an almost retired UAC Peacekeeper, monitoring the designated areas where demons have their established living. One sip of your coffee, on a late night shift, and you notice a red alert on your monitor;
"RED ALERT! Hellish quarantine zone has been breached. RED ALERT! Hellish quarantine zone has been breached. RED ALERT! Hellish quarantine zone has been breached."
You sprint towards the headquarters to investigate...