As part of the popular but unofficial vanilla (circa 2005/2006) World of Warcraft comeback, led by private projects Nostalrius and now Elysium, a brand new, fresh-start server will open this weekend. This will put everyone on a level pegging, playing as if World of Warcraft were released for the first time (albeit a few patches in).
The Elysium PvP Fresh Realm will launch Saturday, 7th January, time TBC, although the suggestion is late afternoon Euro time. Given the expected stampede, however, you may not be playing until evening.
The Nostalrius PvP and PvE servers were resurrected by Elysium in December, saved character data and all, having been closed by Blizzard's lawyers earlier in 2016. They are, after all, against Blizzard's rules. That didn't stop tens of thousands of people playing them simultaneously, however - numbers far in excess of individual, official World of Warcraft servers. Player activity overflowed and so you see the attraction.
Nevertheless, being so populated led to problems, and the resurrected Nostalrius PvE and PvP servers suffered long queues, bugs, glitches and downtime. I doubt the arguably more attractive Fresh Realm will land without a bump.
The Nostalrius-Elysium vanilla WoW servers are free to play on. There's no fee for the game and no fee for the service, although you can donate to mitigate server running costs. If you're up for it, at your own risk I should add, the Elysium website will walk you through what to do next.