Just some procedural level generation, the excess gray tiles were intentional left for visibility.
from top left to bottom right
cellular automata iteration 1, cellular automata iteration 4, Looping Maze, Maze with density,
simple dungeon, template room dungeon, complex dungeon, city block,
mold or fracture growth iteration 1,mold or fracture growth iteration 4, mirrored building horizontal (sides similar) , mirrored building horizontal (sides not similar), mirrored building horizontal and vertical (sides not similar)