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

I have around twentythousand hours in the counterstrike franchise. I played source semi competively, and was moderator on massive 64player severs. nowadays i play occasionally because CS2 just doesn't do it for me anymore.

Faster Than Light

The Witcher two and three

Morrowind and Skyrim

Back in the day i played Battlefield 1942 Desert Combat where I was a top10 player. Also a ton of Unreal tournament.

Heartstone also comes to mind.

Cant forget minecraft

oh Guild Wars...damn put some hours in as well.

Right now I quite enjoy Mechabellum, and im starting to get too sucked in again.

Asheron's Call hit me at just the right age. That was my mmo. I remember people going on about WoW like it was the most incredible thing, but it always felt like a hollow world to me.

I tried many other mmos over the years but none of them ever hit like the first one.

I think I was really just chasing that sense of wonder I felt at my first one, which is increasingly hard to capture as you move forward through life.

Mindustry

Mail order monsters

The Bards Tale (OG)

FF Tactics

Bushido Blade

Vagrant Story

And Terraria most recently.

Most games that spark a Tetris Effect with me, where I'm still playing them in my mind while I've put them down hours ago, are industrial automation games. So the likes of Factorio, Satisfactory, Captain Of Industry.

I was in university and had just passed my midterms and as a treat for myself picked up both KOTORs. Mainlined that shit.

Factorio, Europa Universalis IV, Victoria 3, Baldur's Gate 3 when it was new, and special shout-out to Outer Wilds which hooked me unforgettably

Diablo 2, Skyrim, BL2, BL3, Tiny Tina's Wonderlands, Valheim, V Rising, Oblivion Remastered, D3, and now Helldivers 2. Roughly in order.

Valkyrie Chronicles, I legitimately called off work sick for 2 days when the game came out on ps3.

I played destiny 2 for six years straight.

I finally stopped playing early this year due to burn out.

Now I'm playing Diablo 4 which is a dead game btw.

Balatro

Subnautica, Witcher 3, Far Cry 4, Metro Exodus, Dead By Daylight so far

Star wars galaxies, RuneScape, Minecraft, destiny 2, red dead redemption, dark souls 3, elden ring, bloodborne, and currently dayz

All FromSoftware games including most recently AC6. Also Stardew. I've beaten Stardew probably more than any other game and there's a ton of mods that expand the experience.

I once calculated my Minecraft hours across all platforms I've played on and it's over HALF A YEAR. I was like mega addicted in middle school, I still play often.

servers SUCK now though, they're all pay to win and have custom texture packs that look horrible :(

the best one I've found (that isn't private) is UltraVanilla, and I actually found it from firefoxes "Minecraft Indy wiki redirect" plugin which crashed once and there was a little box on the side which mentioned the server bc the person that made the plugin is an admin of the server. When I joined the discord I had already interacted with several members from other modding discords.
As far as I know im the ONLY person that checked it out due to that popup lol

I don't play on that server because some friends made a different (private) server.

Rust. Its a horribly addicting game thats ruined many lives. Also, Frostpunk.

First was RuneScape, that lasted a month or so. Next was Civ V, that was a couple weeks. I learned my lesson.

Payday 2 probably takes the gold medal for me. I was once playing casually with a friend of me after work, chatting about the day, and when we were about to finish the level we noticed that we damn near broke the world record for that level, a record made by 4 players.

Rocket league. Scrolled all the comments and slightly disappointed to not find this one :/

This was a game I was truly addicted. Uninstalled it many times recognising it as an addiction but kept coming back to it. I feel lucky that I could break out of it. It was THAT addictive. Around 1200-1300hrs on that game.

Urban Terror, it has such a high skill ceiling. Spent many hours just happily running jump maps, let alone all the thousand of games. Thinking of going back.

deltarune, tf2, and uh.. hsr or pgr.

last one was dave the diver. Loved it

Everquest Online Adventures and then City of Heroes.

For EQOA I had 3 CRT tvs and five PS2s with an account for each one going for a couple of years straight. I worked on the road at the time. I was in a different hotel every two months and lugged that around with me. I was in a guild, led raids, powerleveled my and other people's alts.

City of Heroes was similar. Three accounts, I met my ex wife there, was a prominent member in one of the largest Super Groups in the game. I was there from the first couple months of the game until it shut down.

When I found out about the CoH private servers I went back and caught myself slipping right back to the old ways so I haven't touched a multi-player game since.