In 2-D lattice random walks by multiple drunks who can't step onto each other, mathematically I would just say the whole cellular automaton updates "at once".

But to simulate this on a computer, I need to perform computations in some order. This presents obvious complications.

Can anyone point me in the right direction with Google or the research literature? I'm sure I'm not the first person to stumble across this issue, but I don't know what vocabulary others have used to talk about it.