Asellus is an enhanced vanilla style survival server with a fresh permanent map, custom items, and a bunch of new stuff to keep things interesting without drifting too far from the classic feel. We just launched, so everything is set up around starting clean and building up from there.
You'll run into custom mobs out in the world, and some of them can even drop custom items. There are also custom weapons and staffs to collect, plus you get a custom item right from the start. On top of that, the world generation has been upgraded with Terralith, Incendium, Nullscape, Structory, Structory: Towers, and Dungeons and Taverns for a much better exploration loop.
The economy is a big part of the server too, with a shop, auction system, player bounties, jobs, and more to work with as you play. Since the map is permanent, your builds are safe and the world is meant to stick around for the long haul.