Thu Aug 25, 2016 6:06 am by bob
Find what is determining whether it is running already, and make a virtual file for it.
Most of the time it is handled by a mutex. You can find these by using a tool such as Process Explorer (you should run this as Admin), selecting the game process and pressing CTRL+H to view the handles. Scroll down until you find the mutants/semaphores. The most likely one will be a mutant (semaphores controlling game instances are rare). Be aware that there are some mutants that are used anyway, so most programs will already have 3 or 4 of these. The trick is to figure out which ones are the standard ones . Standard windows mutexes are usually named with like \sessions\1\BaseNamedObjects\[xxxxxxxxxx]. You are looking for something that is not a session mutex. Sometimes they are obviously named with the game developer/publisher/game name.
If it happens to be detecting an existing process by executable name, that means you'd need two copies of the executable. This is also fairly rare though.
To make a Virtual File, use the Wizard (on the Wizards menu item).
Virtual File Wzard, select Other, enter the name of the mutex (you should only need the bit after the last \), Hit next, select the characters you want to apply it to, hit OK (or Finish).