See https://adventofcode.com/2016/day/22 Play at: https://advent-of-code-2016-d22.netlify.app/
A game to use to visualize and solve the problem from part 2 of day 22 of Advent of Code 2016.
Starting from the light-blue cell, use arrow keys to move to the G. Moving onto a cell displaces that cell's contents to your previous position.
The object is to move the G onto the upper-left cell.
Cmd-Z to undo. Shortcut: "j" to do a clockwise loop (down, left, left, up, right).