A robot-control puzzle

The goal of this puzzle is to find a sequence of max 4 commands that will move the triangle through the maze and visit all colored squares.

Three types of commands can be used:

  • F0 makes the sequence start over.
  • The arrows (↑, ↱, ↰) move the triangle (forward) or make it change orientation (clockwise, anti-clockwise).
  • Xs change the color of the square the triangle is into the color of the X.

Each command can (but does not need to) have a color. A colored command is only executed if the triangle is in a square of the same color.

If you want to play around with the mechanics, you can do that here. (Disclaimer: I am one of the developers of the site.)


  • Attempting to move out of the board is not allowed.
  • The sequence terminates automatically once all squares have been visited.
  • $\begingroup$ What happens if I attempt to walk off the board? What I can glean from the reference it seems to just die, but I'd like that confirmed (in the answer text). $\endgroup$ Sep 12, 2019 at 13:33
  • $\begingroup$ Does the sequence of operations need to terminate, or is it OK to put the robot into an infinite loop provided it visits every square in the process? $\endgroup$
    – Gareth McCaughan
    Sep 12, 2019 at 13:56

1 Answer 1


This does it:

enter image description here

With the 'finishes when have covered all squares' clarification.


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