Generate a Minecraft network lobby ...

Generate a Minecraft network lobby map with a central circular spawn island made of darkstone and deepslate with a purple crystal beam in the center. Four outer floating islands connected by bridges: Skywars (top-left, ruined castle), SMP (top-right, dark town), Skyblock (bottom-left, lush nature island), Challenges (bottom-right, dungeon island). Dark fantasy style, purple amethyst glow, void sky atmosphere.