Mechanically it's derived from RCTK, while the enemy units are OSR-compatible (with descending AC).

There's an online DM dashboard. docs.google.com/spreadsheets...

The "Precursors" left behind still-active security drones, semi-mechanical autonomous craft that get more dangerous the deeper you go.

Known Precursor drones are catalogued in the "Monster Manual" with code names that will seem familiar to D&D players.