Thanks to everyone that has taken the time to write a comment - I really, REALLY appreciate it! I'll try and answer questions / comments as best I can:
* Undo -- It was planned but I ran out of time. In hindsight it should have been more of a priority.
* Sound -- Yeah, it sucks :(
* Slow -- Each move takes 1.5 seconds to execute, so plenty of room to speed it up. The way things work at the moment meant I had to make every move take the same amount of time to stay synchronized.
* Path overlay -- I like that idea. I use a silhouette of your robot instead of an arrow, along with a glowing trail or something.
* Minimum moves -- Originally you needed to fill the queue before you could move. I left it out for testing, and never put it back in. Whoops.
I'm currently working on an improved version that I hope to release once voting closes. All this feedback has really helped :)