The Grounded player count doesn't rule out single player as a possibility, and simply determines how many of you can set out to explore the backyard together. Handily it allows for a quartet of tiny teens to work together as a team – but if you just prefer to do things at your own pace, then there's nothing stopping you. We've got all of the information on how many other players you can join in the game, and whether you can also tackle this adventure alone.
The Grounded player count lets you and three friends play
The maximum Grounded player count is four, as there are four different teens you can choose to play as – Max, Willow, Pete, or Hoops. The differences between them are purely cosmetic, so it doesn't matter which one you select as none have a particular advantage over the others. However, for your personal base save you won't be able to change your character once you begin, so take a minute to decide which voice and face you'd prefer to encounter for the next however many hours!
There are no split-screen options available, so you'll need to turn to Grounded multiplayer online from the main menu if you want to increase your player count to between two and four players, which includes support for Grounded cross play across multiple platforms. Also note that you can only have one of each teen in a game, so when you join a multiplayer session you may be taken to the character select screen that has one or more options blocked off, depending on who is already present in the backyard.
You can also play Grounded single player if you want
Yes, playing Grounded single player is absolutely a viable option, and there's nothing in the game that you can't do on your own. That being said, there's a huge area of the backyard to explore, with numerous resources to harvest and tough enemies to defeat, so having others to watch your back and fight alongside you is definitely a bonus. If you are going it alone, make sure you're working towards obtaining the best Grounded weapons and Grounded armor, to give yourself a fighting chance against the creepy crawlies.