The playtest unlock condition
Defeat the Relic Destroyer at the edge of the starting system to open Interstellar Warp Drive research in the September playtest. If you can already travel around your home system and the interstellar research is still unavailable, the encounter is the next milestone to check.
Reach the outer system first
The progression described in the developer's September playtest overview starts from Slipstream Drive research. Players then travel to other sectors for cobalt and graphite as they advance through Electromagnetic and Quantum Science. Give yourself time to build up production and prepare a combat ship before heading to the edge of the system.
Check research after the fight
Once you defeat the Relic Destroyer, return to your research and look for the Interstellar Warp Drive. The fight makes the research available. Check what your build asks for before allocating factory output to it. The drive is the step that opens travel between star systems, where the playtest description placed resources for later Astronomic and Xenobiologic Science.
FAQ
Are the Slipstream Drive and Interstellar Warp Drive interchangeable?
The Slipstream Drive takes you farther around the starting system. The Interstellar Warp Drive opens a route to other star systems.
Where does the unlock encounter take place?
The developer describes the Relic Destroyer as being at the edge of the starting system in the September playtest.
Is the interstellar unlock confirmed for the October demo?
The documented unlock is from the September playtest. The October demo announcement confirms expanded research through Electromagnetic Science. Check your build before planning for the interstellar branch.