Note: Most of these dates are also listed with the designation "MTC". This is a reference to "Coordinated Mars Time". Some additional dates appears in Art of Doom, some of these dates appear to be from earlier concepts and in some cases shifted about in the final game see below.
- 21st Century
- Early; Water is discovered on Mars. Very little happens in way of colonization, except exploration over the next century.
- Late; Advanced Rocket Launcher is developed.
- Samuel Hayden is born.
- The Union Aerospace Corporation established an outpost on Mars to extract Argent plasma from the Argent Fracture.
- November 16 - Two Ancient Sentinel statues were excavated (Artifact J46) from Site 1.
- The Argent Tower is completed.
- 6 Months Later - Samuel Hayden transfers his mind over to a cyborg to continue his existence, after his body breaks down due to Stage 4 Cancer.
- The Advanced Research Complex is completed.
- During one of the first teleporter explorations, the Corrax tablets are retrieved from Hell in a UAC Automated Survey.
- 128 - The first Project Lazarus Manned Expedition is sent to Hell. The expedition ends with complete loss of human life, but achieved its mission. The sarcophagus of the Doom Marine is recovered from Kadingir Sanctum.
- Industrial accident related deaths in the Foundry dropped significantly thanks to new UAC safety protocols where employees exposed to dangerous materials are sent to the Lazarus Labs.
- The first Project Lazarus Tethering Operation is conducted.
- Pinkies are discovered for the first time.
- The "vade mecum" compendium is recovered from the Umbral Plains containing information on the Aranea Imperatrix.
- 016 - The second Project Lazarus Tethering Operation is conducted. The expedition ends in an confrontation with the Hell Guard.
- 177 - The second Project Lazarus Manned Expedition is sent to the Great Steppe. The expedition ends with similar losses. The petrified remains of a Baalgar demon is recovered.
- First age
- Second age
- Third age
- Fourth age
Art of Doom (2016)
The Art of Doom has an early version of the timeline from the game its included here for comparison. Note: The book also mentions "AE" designation along with the "MTC" designation but there is no explanation (it is used for the 1366 date, and just talks about it being in UAC's archives).
- c. 149 - First recorded trans-dimensional encounters with demons and humans apparently on Earth.
- 88 - First time demonic races were documented by humans (this may also be associated with Argent D'nur).
- 2049 - Plans for the colonization of Mars begins. UAC, Mixom and I/O Logistics lay down the foundation of a new civilization on Mars.
- 000 - Early tethering operations firsthand discover possibility of species-demon hierarchy.
- 2115 - A region known as the Well is discovered on Mars.
- 2117 - Argent facility construction.
- 2127 - Argent facility is completed on Mars. Samuel Hayden dies.
- 2136 - Advanced Weaponry Division is completed.
- 2143 - UAC automated survey.
- 2144 - Early manned UAC Expedition to Hell.
- 2145 -
- 2146 -
- 016 - They recover a hell warden.
- 139 - Doomed UAC Trans-Dimensional Expedition most of the explorers were set upon by Barons of Hell.
<ref>tags exist, but no
<references/>tag was found