After finishing Doom Eternal, I had to go back and play Doom 2016 as I did not remember how they tied together and it seems like I missed a DLC or something. Doom 2016 ends with Dr Hayden taking the crucible and walking away. Doom Eternal begins with the Doom Guy in a flying castle going after some priests and Dr Hayden has been torn in half. What is the story tying these two games together that I missed?
In 2163, fourteen years after the events on Mars (Doom 2016), Earth has been overrun by demonic forces, wiping out 60% of the planet's population, under the now-corrupted Union Aerospace Corporation (UAC). What remains of humanity has either fled Earth or have joined the Armored Response Coalition, a resistance movement formed to stop the invasion, which has gone into hiding after suffering heavy losses.
The Doom Slayer, having previously been betrayed and teleported away by Dr. Samuel Hayden, returns with a satellite fortress controlled by the AI VEGA to quell the demonic invasion by killing the Hell Priests: Deags Nilox, Ranak, and Grav. The priests serve an angelic being known as the Khan Maykr who seeks to sacrifice mankind for her own race's survival.
According to Wikipedia.
Apparently, this is everything we know. I read several Reddit posts and everyone is complaining about the lack of information about those missing 14 years, apart from speculations.
Things that may be answered in a future DLC, hopefully.