There's a graphical bug on Android 2.1 and 2.2 versions. This bug causes black portions of the screen and random crashing. Samsung Galaxy Note 9, up to date. The 2.1 demo and test build doesn't have these problems.
Can you please provide screenshots of the graphical bug you encountered? As a reference for everyone?
The demo is working fine on my device, I'm not using Samsung.
That's one of the reasons I am rebuilding the game with new scripts. See how upcoming builds work for you.