Fans will recognize that RCT is a descendant of Transport Tycoon, which was created by Chris Sawyer, who ported Frontier Elite 2 from m68k assembly to x86 assembly (and inserted an advert, visible in some spaceports, for “Chris Sawyer’s Transport Game”).
Frontier used a “Scaled Word” datatype to represent the vast interstellar scale of the game, and according to [0] this had a range of 2^65536 ≈ 10^20k.
So there’s something relevant to compare the size of the maze solving time to!