A revamped version of the popular co-op mode for Skyrim, entitled Skyrim Together Reborn, will release on July 8 at 9 AM PT / 12 PM ET.
One of the developers announced the release on Reddit, also stating that support for previous versions of the mods is over. The mod supports 2-8 players. NPCs, quests, and items/equipment are fully synced between players. Upon death in the wild, players spawn nearby, and they spawn at the entrance of a dungeon if death occurs there. You can even play with mods, though it is recommended that everyone play with the same mods in the same load order. Upcoming features include weather syncing, shared map markers, and a scripting API to allow more customizable servers and better mod compatibility.
Understandably, changing a massive single-player game into a co-op experience is extremely difficult. The project is run by students in their free time. It goes without saying that there will be unforeseen bugs and issues. However, the team promises that it will be a massive improvement over previous versions of the mod.
If you are interested in playing Skyrim Together, you should check out the specific instructions on how to download and install it. However, you should also keep in mind that the mod is designed for Skyrim Special Edition version 1.6 on Steam. The devs recommend playing without the Anniversary paid mod pack. The mod is not playable with VR, console, Legendary, and Game Pass editions of the game or with any version of Skyrim before the 1.6 Anniversary update.
Many of the same developers were also working on a Fallout Together mod for Fallout 4. This is currently on hiatus, as making even one of these mods is a tremendous effort.