Says it in the title. In the circumstance I've been testing with, I'm able to return to a glassed Myrellion once. The planet is nuked in KaraQuest 2, finish the Amara fight, and I'm teleported back to my ship. I still have the option to go to Myrellion, which will place me on the planet despite the text blurb about radiation and the airlock. I can freely go around, interact with everyone, as if nothing happened. It only finally locks the planet off if I leave again.
Save file attached post-quest. Cheats are on, but were to unlock Myrellion and get gear to test some scene stuff.
Save file attached post-quest. Cheats are on, but were to unlock Myrellion and get gear to test some scene stuff.