Depending on what kind of addiction behavior you might look at, it's been different games.
For the 'I think about it all the time, and wait for my next chance to get back to it,' an old Minecraft modpack called Per Fabrica Ad Astra was the best. It was the full knapping flint tools through visiting other planets stack, with a good progression tree, so I was thinking about designs for an oil refinery when I should have been sleeping, trying to complete 'just this one last thing' when I should have been going other places, and forgetting to eat because I was making an in-game kitchen.
If you're talking more the 'The world has me beat, so I'm reaching for my...' style, a favorite depressant, Hardspace: Shipbreaker is that. I beat it long ago but I still go back and just do a shift or several when even gaming is 'just too much.'
And if it's more the style of a stimulant, BPM: Bullets Per Minute. It's a great way to hit a high speed flow state. Boom boom chik, boom boom chik