In order to find out what is causing this, you can Debug the app and send us the log files. To Debug a port, select it in your Porting Kit Local list and hold Shift. Now, the Play button should change it name to Debug. While holding Shift, press the Debug button and play the game normally. At the end, when the game crashes, use ⌘ + Q (or ⌥ + ⌘ + Q depending of the port) to force close it. You can also try ⌘ + Tab if it stop to respond completely, which is rare but can happen (that will minimize or resize the app, so you can close it with Finder).
After closing the app, Porting Kit will ask if you want to see the logs. Press yes, copy them and send to us, so we can help you