The thing is, Minecraft has multiplayer support, built into the game. Fallout's engine doesn't have anything. Obsidian/Bethdesa didn't even try to add any sort of 2nd player provisions- god knows how much more buggy the game would be with two players messing things up. Minecraft runs slow on your computer because of how minecraft works- it's got blocks! In most games the ground is just one object, but in MC it's thousands! That each have to be tracked separately! It's not that the Fallout engine needs performance improvements, what a modder would have to do would be: 1. Figure out a way to HAVE two players in the first place. 2. Figure out a way to control the second player(on the same computer? Same monitor? First person? LAN?) 3. Figure out how to make NPCs respond to the second player. 4. Figure out how quests will work when there are two people playing them. 6. Find and fix the millions of problems that will come up once hes done. The closest thing to co-op is
, and even that isn't full co-op - the second guy is playing on the same screen on the same computer, using a joystick. He can't aim, talk, use menus, or do anything other than move, switch guns, and shoot. Point is, this would involve a LOT of work, far more than most mods, and just saying "I want it like this make plz" is a bit insulting. If you really want co-op, you could offer to pay, or try doing it yourself- I don't think there are any modders out there that would just try doing this one.