I've checked and double checked and checked again. every little square in and around this room has had the blocks removed and replaced with my blocks, backround and foreground. the room is well lit. yet still the monsters spawn. I need to expand my frickin base deeper how the hell do I fix this?! Screenshot provided below:
The game doesn't run on Minecraft or Terraria rules and monster spawn prevention isn't fully functional. Monsters typically spawn slightly off-screen, but player placed blocks and natural blocks alike don't always load up before monsters find an empty spot of air to spawn in. This causes monsters to spawn in places that they shouldn't, with the exception of dungeon/town no-spawn zones (which sometimes have altered gravity). Atleast that's my understanding of it. Barren worlds do not spawn monsters, npc, ores or treasure of any kind. They are ideal for constructing if you don't mind the bland backgrounds.
Well THIS is my base, and its HUGE. what you see in the screenshot is the lowest level and the ONLY place mobs spawn. The base extends into a large, wide tower stretching from underground to the upper atmosphere, and I'll reiterate, THAT ROOM in the screenshot is the ONLY place they spawn.
That is rather odd. Maybe try putting some furniture or storage in it..? I don't know. Monsters don't seem to like decoration.
Well the screenshot had furniture in a completely enclosed area and mobs still spawned in that part of it. It could be a depth related bug.