Specifically:
Minecraft running in Minecraft https://youtu.be/-BP7DhHTU-I
or
Game of Life running in Game of Life https://youtu.be/xP5-iIeKXE8
Bonus: Digital clock implemented in Game of Life https://youtu.be/3NDAZ5g4EuU
Surreal because it makes it apparent that our universe could really be emergent behavior from a simple set of rules.