By massive worlds I’m envisioning something like Planetside 2 where you have incredibly large maps with large (>300) players at a time. Can Unity handle something like that or is it asking too much of the engine? And then, if Unity can handle it, are there networking libraries that could help facilitate this?
For something like this, use Photon.
Well… networking has NOTHING to do with the size of your world. I am working on an mmorpg with the intent of having over 2000-3000 players on one server at once. Of course you only tell the client about the characters near your character, and ignore the characters 1000 meters away you couldn’t see anyway. So… absolutely. This is definitely possible. You just have to design your networking system a certain way, and not use Unity’s base networking system. You can use mine if have a decent amount of coding experience. The trick is… to only send the right data to the clients and not send unnecessary data. Ask me if you need more help with that.