RollerCoaster Tycoon Optimizations are Insane

A breakdown of three key optimizations used in RollerCoaster Tycoon (1999), written entirely in x86 assembly by Chris Sawyer. The optimizations covered are: (1) minimizing memory per NPC by using 1-2 bytes for money representation to fit within the 16MB RAM constraint; (2) replacing multiplications and divisions with bit shifts to save CPU cycles on 90MHz processors; and (3) avoiding expensive pathfinding (Dijkstra's algorithm) for most agents — instead using random wandering, with limited-depth pathfinding only for mechanics and guests trying to exit. A fun detail: buying a map in-game increased a guest's pathfinding search depth from 5 to 7, helping them find exits rather than rides.