I recently discovered (thanks to a friendly player) a small flaw in the testing version that would have prevented the game from running. The reason it was not caught sooner is that players running the testing version would have most likely run the default version first, thereby creating the necessary configuration file. If the testing version had been run without this file, it would have loaded a black splash screen, and the main menu would never show up.
The latest testing update (still called 3.7) fixes this issue.