For non-online games, my favorite time sink is Slaying the Spire. It's a pretty simple rogue-like card game, but man, it's addictive. I think I have over 300 hours in it.
Cool, I was playing ranked for a bit early on, but it just seemed tough to follow the metas. I enjoy watching on twitch though.There's "ranked", which I play most often (you go up and down in rank with wins and losses), or you can play another player in the same way, but it doesn't count for your rank (I play that to test new decks) or "Tavern Brawl" which is a constantly event where there's unique rules or card sets based on the week (or whatever term they choose to do them for).
Each expansion tends to have some single player adventures that can kill time for a little while.
I find it fun just playing and doing the daily challenges for gold (which you can use to buy card packs). I don't like to pay cash for card packs very often (I've probably spent $50 total over the span of a few years) but it's interesting trying to find new combinations of cards that work well together.
Cool, I was playing ranked for a bit early on, but it just seemed tough to follow the metas. I enjoy watching on twitch though.
My stages of 'video game' life ....