A new official patch has been released that fixes the CPU core issue. If you are having trouble launching the game, update your game to the latest version. Note that some players have reported that this update clears Steam achievement data (UPDATE: supposedly fixed).

For many years, Epic Mickey 2: The Power of Two has been unplayable on CPUs with more than 4 cores without tricking the game into thinking it was running on an inferior CPU. Thankfully, an easy fix was posted on the forum by helix666. Original forum post: https://steamhost.cn/steamcommunity_com/app/245300/discussions/0/617320167968970644/?ctp=6#c1735507058424713699

Originally posted by helix666:

Have the same problem as many others and did a small investigation about it.
It seems that the game creates threads based on count of physical cores, but they never tested it with more than 4 cores.
The game engine creates threads/mutexes and use WaitForSingleObject to synchronize threads, the problem that additional mutexes never got released(deadlock).
Dunno why they can't fix such trivial problem for years. If they can't make proper synchronization, just put one line of code(few minutes work) after GetLogicalProcessorInformation call and limits maximum cores count to 4.

I did a small fix for myself and want to share it.
I can't give any guaranties that it will work for everyone, but it fix issue for me.
Just put dinput8.dll from this zip[www.dropbox.com] into the game dir (like "steamapps\common\Disney Epic Mickey 2") where DEM2.exe file locates and run the game normally.
The second file in this zip is a source codes, so if you have VS you can compile dll by yourself.

How toes it works:
It uses dinput8.dll (game uses it and load to memory) to make a hook for GetLogicalProcessorInformation function.
The hooked version of function always returns that your system has 4 cores for processors which has more than 4.

Full credit goes to helix666 for creating this fix. Posting it here as a guide in hopes that it gets more visibility. I can't see this ever being fixed by Disney, so it's important that this gets out there.