Ratazong,
Thanks. I think Robbo Rally would be great but even if I used the entire time slot, I don't think it would work. I said "something like a Caeser Cypher" because I wouldn't want the algorithm to always be the same single operation. I was thinking about making the letters different colors as well as inscribing them in different shapes. So each letter required going through a short algorithm with conditional branches (if green, add 3 to the number of places in the shift).