You must ascend, and you can cheat that in singleplayer. I think it was: cheat ascend 1 2 and 3 but i dont know with 3 gives you acces to ragnarok no spaces between ascend1 and ascend2 and ascend3
Single player i cheated the required artefacts and stuff and went god mode so i could play out the end game tek cave and alien mothership, didnt take long at all was good to do!