What Gorilla Simulator is
Gorilla Simulator puts you in a big open world as a gorilla, alongside everyone else who joined the session. You run around the map, throw rocks, pick up bananas, and grab hats you find along the way. The whole thing is built on the developer's own strange ideas, and the game says outright not to take any of it seriously. Expect a loose, silly sandbox rather than a serious survival game. Random events fire off during play, so the map keeps changing what it asks of you while you wander.
Playing together with your group
Sessions support up to 30 players, so a full Discord group can pile into the same world without splitting up. Voice chat is built in, which means you can talk to the other gorillas directly instead of coordinating through text. That makes it a natural pick for a group that just wants to hang out, mess around, and react to whatever the game throws at them. Everyone shares the same map, so you can team up on an event, race each other to a pile of bananas, or just throw rocks at nothing in particular while you chat.
The mountain and the events
The main thing to aim for is the mountain. Climb it and you claim the Pineapple, which triggers a random event for everyone. Beyond that, the game runs a stream of events you complete as they come up, and collecting bananas and hats gives you small goals to chase between them. Nothing here is a strict campaign, so your group sets its own pace: wander and socialize, or push for the mountain and see what happens next.