TL;DR
Demolishers on Vulcanus migrate every X days, crossing the planet and adding consistent pressure to players in way unique to the planet.What?
Every 20-30 in-game days, demolishers can migrate slowly crossing the planet west to east, regardless of existing territory / safe areas. Migrating demolishers would not seek out player structures unless attacked, but would still destroy structures as they pass.Size of demolishers would be smallest at the equator (latitude of the player's landing area) and grow larger the further north and south the player goes.
Areas cleared of player structures would be repopulated by a demolisher, barring the original safe area.
Difficulty option causing migrating demolishers to increase the next wave in size when slain, as the player would be taking the smaller demolishers out of the gene pool.
Why?
Recreating the feeling of awe and fear I felt upon first seeing a demolisher.Adding time pressure to Vulcanus to match Nauvis and Gleba. Time pressures add challenge to mega-basing on Vulcanus, and provide motivation to reaching a high SPM on the planet rather than relying on a trickle of science while working on other planets.
A significant defensive challenge coming from a reliable direction and schedule provides a reason for players to make elaborate defensive setups and have said defenses be tested in ways that biters and pentapods cannot provide.