The adventure isn't over yet!
You can play the Human in a spinoff named "Interea", which happens during the last 9 months of the game, when Amicus takes you to the Moon tour. Then you can play Khemia, a "half-sequel" happening two years and a half after Adastra. You play as Scipio in Khemia though, not as the human. Khemia is more of a Scipio x Neferu romance thing (I think so...) and it takes you to the actual Khemian planet