Looking for a game that has infinite playability?

As title says, I’d like a game with essentially infinite playability ? Like something I can at any point play and or drop and then come back to. Like right now I have no idea what to play and don’t wanna spend much money, so I’d like a game that I could get into relatively easily and play for say 2-3 weeks then drop if something else catches my interest for some time but when I’m done with that I can game back to the infinite game? I’m probably not explaining this super well but I hope the idea is mostly understood. I’d just like a game that can be played or not played(?) at anytime interchangeably with minimal effort.