Stunt Car Racer for SuperCPU (C64) at 50 fps

Stunt Car Racer for SuperCPU

Grab it at CSDB: https://csdb.dk/release/?id=230122

This project is the fruit of playing around in the evenings for a few weeks, most of which was spent studying the code of SCR out of curiosity. At some point I realised that the physics time step could be adjusted through a single hook that handled the integration of every variable. I immediately thought to myself that a proper SCPU adaptation with silky smooth animation might be much easier than I previously assumed. I quickly found another important physics hook that affected the forces generated by contact with the road, and the rest was just fixing a bunch of minor issues over a few additional evenings.

The original game steps the race clock by a fixed 0.14 seconds per update, so I decided to divide the time step by 7 to get a solid 50 fps output with equivalent timings. As a result, the game has basically the same speed as usual during practice rounds (the original takes almost exactly 0.14 actual seconds per update), but it plays slightly faster when racing against an opponent (where average update times can go as high as 0.18s in the original, especially right behind the opponent). Thanks to the extra computing time left, I could also crank up the view distance as well as the LOD to burn the remaining cycles.

I decided to provide an alternative "turbo" version as well, where the time step is only divided by 5, for those who want a more thrilling experience. The clock still follows the real time, so race times are going to be shorter with this variant.

Due to the nature of the changes some of the mechanics cannot work exactly the same way, so I made a best effort to match the original experience. Notably, damage calculation can only be approximated, and may need further tweaking.

Disclaimer: I don't have real hardware, so I could only test in Vice.