The game starts out with about 40% memory usage and after about 15 minutes of game play, it runs out of memory (at 100%) and crashes.  The saved game cannot be opened once it runs out of memory.

This video shows what happens when it gets close to 100% memory usage:

https://www.youtube.com/watch?v=pWm5W6KrdoU

After the crash, when one tries to open the saved game, the following error message is received:

No modification or alterations to the game – just the original game itself directly from Mojang.