Basically a trail of little squares (footprints) that spawn wherever you go. (If you're on the ground, of course) Is this possible?
An idea I have is that is spawns bots wherever you go that have 50% transparency, and just look like 2D squares. This would allow you to 'kill' your footprints (hide). The bots would spawn with 100 Health and would deteriorate at 1 health per second. This would be even better if it only spawned when you walk on certain bricks.