The original Roller Coaster Tycoon is famously written in assembly.
Sawyer wrote 99% of the code for RollerCoaster Tycoon in assembly code for the Microsoft Macro Assembler, with the remaining one percent written in C.
This always blew my mind, especially when struggling around with things like cmu bomblab back in the day.
I haven't thought about assembly in a long time, and not sure if I want to ;P
Looks like a nice detailed walkthrough though!