Tetris kind of has a long running title on this topic.

I dont even like tetris that much, but it has captured the attention of generation after generation.

It’s probably one of the only games you could open in almost any setting and have people wanting to play it.

Minesweeper and Solitaire.

Spider Solitaire. Been playing it for like 20 years.

DayZ is a good candidate. It’s over 10 year old game that’s still getting regular updates and breaking total player records. There are streamers with well over 20k hours put into it and there are still unique moments happening to them that you can’t really experience in any other game. Also it’s a game you can’t even win. You’ll always die eventually and have to start again from zero.

Games that have relatively short run cycles and are still the “complete game” each cycle. Tetris, solitaire, minesweeper are the OGs of this but bullet heavens (aka swarm survivor), and rogue-like/lite games can have this life cycle too.

The primary reason IMO is that you can feel accomplished and satisfied with the gameplay and the story more or less isn’t important. This allows you to pick it up at anytime down the road, play it, feel accomplished, and don’t need to recall story elements. The time sink required for these games also makes it important due to the fact you can squeeze them into your schedule if you only have 1 hour, or in some cases even 1/2 an hour. The loss for abandoning midway is also inconsequential.

Based on the amount of hours I’ve put in: Factorio or Kerbal Space Program

Both share the sandbox theme where you can play around and try weird stuff in your own tempo. You define your own goals, instead of just going for a stock goal.