So click on singleplayer, go to scenarios, then modifiers click one of these modes:
Superhot, Top down, Zero g, or living dead. Exit out of singleplayer, go to multiplayer with selected mode(s), create a server, then let someone or friends join, and BOOM you got one of those modes in multiplayer.

Boom you did it (idk if someone made a guide like this so i'm sorry if this seems like a copy).