I tried your suggested steps and it worked but, the game has no audio.

Alternatively, it's WAY easier to just drop into Nexusmods and grab the mod they have that fixes the CTD Error, Drop it in and call it good.

I agree its exceptional considering it came out in 2007. However i did the core setting once over the taskmanager and i never had to change it again. It now only uses 4 cores everytime it runs and it works perfectly for me.

Of course you can, for me the point is that if i set 4 cores on steam.exe insted of prototypef.exe is "if" my game crash or if i take a break i don't have to retick the 4 cores when i launch the game again.
There are multiple ways to achive the game to run without startup/loading crash, this is just a quick and dirty way to do it.
You do whichever suits your needs the best.

I'm also working on a new solution without the need to set cores and is per game and one time set up, but i'm still testing it.

Glad you could play, Prototype is great game.

I did this too however u can do it for prototype itself you dont have to do it for steam. This way u can just give it 4 cores and it runs perfectly. Theres also custom screen resolutions for prototype that you can find pretty easily. With these 2 changes the game runs perfectly for me. I had one crash so far in 25+ hours and that one was expected.

Funny that I see this post right after I found the solution myself. I have a AMD 5700X cpu, 8 cores 16 threads. It kept crashing when I tried booting the game, I speculated that it could have been the multi threading so I turned off SMT, once the OS saw only 8 threads the game booted up and ran perfectly for me.

PC Specs:
CPU: AMD Ryzen 7 5700X
Ram: 32GB (8GB Sticks) Patriot VIPER 4 Series 3000MHz Dual Channel DDR4 with 16-18-18-36 timings.
Motherboard: Asus TUF Gaming B550-PRO
OS drive: ADATA XPG SX8200 Pro 1TB
OS: Windows 10 Enterprise N, Version 22H2, Build 19045.2965
GPU: Gigabyte Radeon RX 7900 XTX Gaming OC
AMD Driver Version: 23.7.1

window 11 user here (rtx 4090, ryzen 7950) forget any other hack/mod/patch floating around to make this game working. for me it makes no sense BUT assign the cores as mentioned for steam.exe (not the game exe itself, this doesnt work) is the only way to launch the game on windows 11 22h2.

my error (in case you'd googled it) was crash of prototypeenginef.dll, Version: 1.0.0.1, 0xc0000005

Good Job

I wrote this Launcher for this game.
{LINK REMOVED}https://github.com/fcomeraz/SteamPrototypeLauncher

Glad it worked

Enjoy