subtle is a manual tiling window manager with a rather uncommon approach of tiling:
Instead of relying on predefined layouts, subtle divides the screen into a grid with customizeable slots (called gravities).
For better understanding, the default config uses a 3x3 grid and maps each gravity to one key of the numpad. With those keys, windows can be moved directly to the desired gravity - the same can be done with tagging rules in the config.