Mars Core

Mars Core is the seventh level of Doom Eternal. Beginning at the orbital defense base on the moon of Phobos, the Doom Slayer battles an ongoing invasion while intending to reach the core of Mars, where an ancient Night Sentinel slipgate resides. Through the use of an orbital weapon system known as the BFG-10000, the planet Mars itself suffers massive damage, directly creating a path to its core.

Pre-release
A shortened version of the first half of Mars Core was the second level of Doom Eternal to be displayed to the public in the BE3 reveal on.

The noticeable differences from the reveal to the final product includes the following:
 * The exclusion of Samuel Hayden throughout the level, presumably to avoid spoilers.
 * The exclusion of the Doom hunter near the BFG-10000, in which it is undergoing refinement phase at that time.
 * The entrance to the BFG-10000 is accessible in the reveal, which reveals an arch-vile at the other side of the door with the Doom Slayer pulling out and swinging his Crucible blade as the reveal ended in a cinematic fashion. In the final version however, the entrance is inaccessible, as the Doom Slayer takes the maintenance hatch is taken instead. Both the arch-vile and the Crucible blade are also introduced later.