I have been trying to come up with a new robotics challenge that will be:
- Unique
- Cheap and easy to assemble at home
- Interesting
For item 1, I think we older hobbyists have done enough line-following, sumo, etc. I wanted something that nobody had ever done before. 
About number 2, I thought about ways to assemble a maze for a traditional fire-fighting contest, but never got anywhere. But then I thought, how about a smoldering tree in the forest. I had some 3/4" wooden dowels cut into 4" pieces and a 3'x4' peg board. I could anchor the dowels with 3/4" wood screws and create an irregular maze.
Here is what I think makes it interesting:
- Laying out the 'forest' randomly would be a good exercise for AI, making sure a path was possible and specifying precisely which holes to use. You could do it at home for practice but a new field could be generated for the actual contest.
- The robot hardware design would involve motion and shape as well as 360 degree sensing.
- The candle might disappear from view behind 'trees' as the robot moves.
- Random search might work, but software would need to be creative to avoid getting stuck. (I've been playing with Mecanum wheels driven by a Pico; see video below.)
- An alternative contest might be to just place the robot down in the middle of the 'forest' to find its way out.
For illustration, this few-seconds video shows my Pico-powered, Lego-hybrid robot crashing into some pegs.
