My Time at Sandrock does not feature multiplayer or co-op, but it could be coming soon

sportskeeda.com:

My Time at Sandrock is another life simulator by the developers at Pathea, but players have to go at it alone for the time being.

The fan base welcomes multiplayer in games like these. It makes for good trust-building among friends and even some great content when that trust goes sideways.

For now, though, My Time at Sandrock will not have a cooperative mode or any sort of multiplayer. There's a strong chance it will arrive in the future when the game is fully released.

It was made very clear that multiplayer won't be around in the Early Access version of My Time at Sandrock. The game was launched on May 25 in its Early Access stage, and no official full launch date has been given.

The developing team confirmed that cooperative play, and any sort of multiplayer, won't come during this phase in a Steam discussion post:

A question-and-answer portion on the game's Steam page sees the question asked of how long the game may be in Early Access. The answer given indicates when multiplayer may arrive:

A roadmap for multiplayer mode was provided through the Pathea Games YouTube channel. A smaller-scale cooperative experience is the plan, and testing for it may arrive as soon as August.

A global test could then follow later in the month if all goes well or perhaps the following month in September. The goal is to have enough test periods so that they feel comfortable releasing a multiplayer mode in December.

So, it may not necessarily take players to a full release before any multiplayer aspects are added. There was also no mention of a larger multiplayer focus, with just a four-player cooperative mode brought up.

If everything goes as planned, My Time at Sandrock will have some sort of multiplayer by the end of 2022. Otherwise, expect it