How to make work an app/game for mountain lion (10.7 or more) on snow leopard (10.6)?

I've encountered some games/apps that won't work on a Mac OS 10.6 because designed for 10.7 or superior.... nevertheless I've heard that you can modify a small text file in the app to make it work still for the 10.6.....but how specifically? do you have other suggestions?

In the specific I'm interest in making this XCOM game work
Minimum Requirements
Processor: 2.0Ghz
OS: Mac OS X 10.7.5
RAM: 4.0GB (or 8 if you have an NVIDIA 320m)
Graphics: 256MB

On my system:
Processor: 2.4Ghz
OS: Mac OS X 10.6.8
RAM: 4.0GB
Graphics: NVIDIA GeForce 320M (256MB)