It's been a while since work was started, so I figured I would post an update on how the game will likely be finished. Basically, there will be two different scenario types when starting: the "Main" campaign, and "Another" campaign.
In the Main campaign, the player finds themself marooned on a specific planet, with the world itself being hand-crafted and a number of options for various levels of difficulty and randomization available at the start. Certain specific enemies, areas, and bosses will be present in this scenario though their placement, difficulty, and variations can be controlled to a degree before the game begins. By default the base world will be the same each time if no randomization of difficulty settings are changed, and it's intended for the player to try or finish this scenario before moving on to the next.
In "Another" campaign, the player is sent to a completely different planet. While the goal remains the same (find lost technology beneficial to humanity and escape) the destination and journey is changed each time. New bosses, enemies, and areas can appear and everything is randomized to a basic level by default, and the player can tweak difficulty and randomization settings as always.
Completing either scenarios (therefore successfully returning to the Milky Way and Earth with technology beneficial to humanity) improves the situation at home and increases Earth's standing in the cosmos. Eventually, humanity may be accepted into an increasing number of other civilizations, and those clinging onto hope back on the dystopia of Earth might be brought out of the dirge they were in before the story began.