Simple mathematical relationships are the basis for the increased complexity of the puzzles in RO. While designing RO, we were able to solve the majority of the puzzles during the design phase. But we continued on through the production phase without having solved the final puzzle, Expert 5. We knew it was solvable, because the math was telling us so, but it wasn't until last month that it was finally solved, with confirmation.
Summie of Redmond Washington made this photo evidence available to us, confirming that she had indeed solved Expert 5. She should have entered our Expert 1 Contest.
Theoretically, Expert 5 should be solvable in less than 555 moves, much less. But, it is an Extreme visual puzzle, and that visual complexity can make it very challenging to decipher a solution in the minimum possible number of moves.