BeamMP started late 2019, with the first version being based on JavaScript, and still using the old Bridge (which at the time didn't have a server selection menu). - The bridge was used to suppliment the ingame UI mod, it was the cause of a few problems, and ultimately bulked the ease of installation.
It later evolved into a more complex version, featuring a revamped UI (added palyer list, ping, and chat), and the Bridge got a server selection menu. It was still very primitive and hard to use, the syncing was bad as players only teleported. It was still cumbersome to get up and running, requiring a mod to be installed into the mods folder, and for the bridge application to be run simultaneously to the game being launched... sounds complicated? it wasn't ideal.
Now the MP mod has been completely rebuilt in C++, introducing a brand new UI fully integrated into the in-game UI, including an in-game server browser. Everything has been packed into a single and easy to use .exe, resulting in a one-click-run mod, making for a super easy to use multiplayer experince. It's just like openining the vanilla game, but now you can play with your friends!