Changing the size of memory or changing the ROM version forces a reset of the PET.
The emulator has an IEEE-488 device at address 8. It can be used load and save (.prg) files.
Some programs don't run on ROM1 and some require more memory than the default 8K.
DEMON! is a game of tag played on a screen full of PETSCII obstacles. Every time the player (a circle) catches the demon (a different circle), a new opponent will spawn. The game flows quickly, and the demons are hard to catch. The keyboard buffer is the true enemy in this game—your buffered movements will cause you to overshoot your quarry if you aren't careful.
In addition to the keyboard controls, you can use a joystick to play this game. I don't think PET joysticks were common, but they were an option.