RuneScape

RuneScape, RuneScape 3 to most players, is the branch that kept updating while Old School restored the 2007 build. It has more skills, a full action-bar combat system with abilities and cooldowns, and an enormous quantity of content that has never been rolled back, including a quest line that is among the best-written in any MMO.

The trade-off is coherence. Two decades of systems layered on top of each other make the interface dense and the progression paths hard to read from the outside, and the monetisation is more aggressive than its sibling's. If you want the larger, stranger, more feature-complete version of this world, it is here. If you want the disciplined one, play Old School.