After finishing all the dark matter levels both the main game and the dark matter game have moved onto an empty "Chapter 6" field (it says Chapter 6 at the top but there are no levels and no way to move backwards to the previous levels). This is obviously not a critical issue as I can easily reinstall the game and unlock all the content but I thought it worth mentioning.
A second minor bug that I've encountered a handful of times is a pause bug that will stop the game until I go to menu and hit resume, again very non-critical.
