I like Counter-Strike: Global Offensive, but I loved the original Counter-Strike. While CSGO is the prettier, more polished version of the same set of ideas, so many of the maps, so much of the feel that I loved, isn't present in the latest iteration.
The original Counter-Strike is still available to play, but its final update, 1.6, isn't the version I want either. I want beta 5.2, or thereabouts, from back before Valve bought the game and its rougher edges got sanded away.
That's me. But I'm here to ask you: what live service game would you like to see relaunch and preserve an older version of itself, as World Of Warcraft: Classic has? And what version would you want?
A launch version of City Of Heroes? Star Wars: Galaxies prior to its New Game Enhancements? Team Fortress 2 after the Sniper got the bow-and-arrow but before *gestures widely*? Warzone pre-nuke? Spelunky 2 before Olmec got nerfed? Darkest Dungeon in the earlier months of its early access development?
For me, I want Counter-Strike in its messy middle period because later betas and sequels removed as much as they added. Early betas had the Assassination mode, for example, in which one player was a mostly defenseless VIP that the Counter-Terrorists had to defend. There was also Escape mode, umpteen maps more awkward (and interesting) than de_dust2, and the never-fulfilled ambition of vehicles in de_jeepathon2k.
I know that Counter-Strike jettisoned a lot of those modes and maps because they didn't work, in one way or another. I also know that there are a lot of modern conveniences that it would be difficult to go back and live without.
But there's beauty and potential in broken, unpolished things, and like with WoW, sometimes the inconveniences lend a lot of character to an experience. (And I'm pretty sure I'm not just missing being a 15-year-old, because that was rubbish.)
In your answer, it might be tempting to suggest a game that's outright closed down, its servers long since binned. That's fair enough. If you want Club Penguin back, then by all means explain why. But try to drill down to a specific version or era of the game you pick, because I think that's the more interesting question. What did you miss even before the final axe fell, if it ever fell at all? Let me know in the comments.