Prototype Playthrough — Episode 1: Bioweapons in the Belfry

To run this game on Steam, you need to create two .bat files, one to run Steam proper, and one to run the game. You will most likely need to modify the path to the executables shown below to match your installation locations.

Steam.bat needs to contain the following:
start /affinity AA D:\Steam\steam.exe

Prototype.bat
start /affinity AA D:\Steam\steamapps\common\Prototype\prototypef.exe

To create a .bat (or batch file) open notepad, add the text above (one per .bat file) and match it to your install location. Then, when you hit save as, select all files *.* from the drop down menu, and save it as Steamcore.bat (for the steam batch file) and Prototypecore.bat (for the Prototype batch file). You can name the files however you want but the extension needs to be .bat

Once done, close Steam (if it is running) and run Steamcore.bat. Steam will launch.

Then, run Prototypecore.bat and, hopefully, enjoy the game without hitches.

Once done with your play session, make sure to exit Steam and restart it normally before running any other game. If you don't restart, Steam will be running only on four processor cores.