Stardew is a great cooperative game to play with others on your downtime and is easy to learn. There are a lot of resources within the game to help anyone who is new to it.
You honestly don't need my review to know this game is good so I'm just going to add some minor points to what every review is already saying. First, the game has some amazing expansion mods for those who want them, the best of which is Stardew Valley Expanded (SVE).
Second, my only complaints about this game are that the days feel really short so if you have any kind of timer anxiety that can be rough, and if you play on multiplayer there is no pause when you enter a menu. Although there's probably a mod out there for both of those things.
Anyway. Buy, play, enjoy :3