Reach up to the skies or dig deep below, expand your base vertically... If you're into that kind of thing. Original by Simcra, ported to 0.14-0.16 by Erdbeerbaer. Port to 0.17 started by DeltaNedas and continued by Danacus.
Situation: Omnimatter installed. I disable ALL ores gen. Enemy is disabled.
put stair to go down one layer , surface. Omnimatter's ores spawn . Enemy also spawn.
Ore generation is kind of a mess in factorio. The game isn't designed for different oregen of different surfaces, so mods have to work their way around it. So I don't know if this is a bug or if it is expected behaviour with this combination of mods.
