Since I was having so many issues running the game on 1.1.1.5879, but managed to get 1.1.1.5767 (from a Crysis: Maximum Edition physical disc) working for me, I spent a bunch of time trying to isolate what was necessary for others to downpatch to this version as well.

I've outlined in the video above the necessary steps to get the game working properly on this patch version, but I'll summarize here as well.

1: Open the Crysis install folder on your PC.

2: Delete the "Bin32", "Editor", "Game", and "Pb" folders.

3: Paste in the "Bin32", "Game", and "Support" folders from the 1.1.1.5767 downpatch folder.

Added note: you will need to use software such as Dxtory or Rivatuner to cap your FPS, because this patch does not have an option to turn on Vsync, and the AI's pathing breaks in strange ways if your framerate is too high. (This sounds like it would just be silly, but there are ways it can softlock a speedrun).

I've done a full test run through the game on my own PC, after following these steps on a fresh Steam install of the game and didn't run into any problems, but this is as far as I'm able to test it by myself.

This should only be necessary for anyone trying to speedrun on a modern AMD CPU. Anyone with an Intel CPU can use the existing 1.1.1.5879 downpatch without issues.

1.1.1.5767 Downpatch files: https://drive.google.com/drive/folders/1lzqEDY9OB-CvRLmhqizZ5YS2nWT9FYHv?usp=drive_link

c1_launcher: https://github.com/ccomrade/c1-launcher/releases