Four different kinds of luck.
The four buttons do noticeably different things. Knowing which is which is the difference between steering and fishing.
Surprise me: Stays on the system you are looking at and rerolls its parameters, seed and palette. Use it when you want to work one idea properly.
I’m bored: Changes everything, system included. Sometimes it will build you a stack of two to four layers, occasionally with a few parameters already animated.
Remix: Moves to a different system but carries something of the current design across with it.
Evolve: Nudges what you already have instead of replacing it. Press it repeatedly and you walk somewhere, slowly.
Every system draws from a seeded generator and never from the browser's own randomness. That is the whole reason a design is reproducible: the same seed gives the same drawing, on any machine, indefinitely.