Use turbo mode! Arrow keys or WASD to move, z to pick a tile (enter a number from one to five), click a tile to set it to the selected one, move speed slider to change speed.
Walk Walker, assuming I don't give up halfway through creation, will come out at some point in 2020. Everything to the left of or below the "spawn point" is tile one and is not editable. Changes: 12/20/19 - Beta 1.0.0 - Game released with scrolling, five basic tiles, and simple editing.