Commodore 64: Mercenary

summary

The article provides an exhaustive, byte-accurate breakdown of the 1986 Commodore 64 open-world game Mercenary. It examines rendering limitations, flight models, object catalogs, and underground rooms by porting game routines and running them in simulators. Notably, it highlights a newly uncovered 41-year-old bug where an invisible grass patch teleports the player to the Colony Craft because code checks omit height values. The interactive site lets readers test these routines and inspect original memory structures.

key points

1. An invisible patch of grass near the crash site triggers a teleport to the Colony Craft because the lift interaction code fails to check altitude.
2. The game uses a double-buffered 160x136 multicolour bitmap screen, achieving 4 to 5 frames per second on the surface.
3. Objects outside the city are handled as fixed entities because building models are only loaded for central grid squares.
4. A permanent non-interactable ship belonging to the Palyar commander's brother-in-law laps the city endlessly at altitude 500.

who should read it

Retro game developers, reverse engineers, and Commodore 64 enthusiasts.

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