This thread is here to answer every post on how to make an MMO in UDK. I intend this to answer the question once and for all, that way we dont need to see thread upon thread about this subject, as its causing quite a lot of hate on these forums, which should be a nice and helpful environment.
----No, you can't. UDK only (officially) supports a maximum player number of 64 per server.
Can i make a MMO in UDK?
--- The Short Answer ---
Can i make a MMO in UDK?
--- The Long Answer ---
Yes, if your willing to take on the following tasks, you can, in essence, create a Massively Multiplayer Online Role Playing Game with UDK.
1) Create a new server/client structure which supports more than 64 players per server, you'd be looking at allowing at least 2,000 players per server to be considered "Massive".
2) Develop an entire world inside the UnrealEditor. However the editor is not well designed for MMO development, features such as the terrain system are not well developed for the scale you'll need for an MMO.
3) Create a massive amount of content. Lets put this into persective. To match the character density of a game like Warhammer Online, you'll need around 50-100 non-playable character models per location, and those are just quest givers, they need dialogue, quests to give, and each one has its own material or set of materials, its own animations, and so on. Thats just non-playable characters, now think how much content a player needs to customise his character.
4) Money. You'll need a lot of money, not to pay your team. You'll find loads of people willing to spend hours making an MMO in their spare time. But you'll need a server from day 1, those are not cheap, and by the time you come to launch, your going to need 10+ servers at least, for a smooth launching of your finished game.
5) Time. MMO's take years to develop when working in teams of 100+ paid staff members. If you can get a team of 20 you'd be doing well for a non-paid team, so that should take you... 15 years? Good luck finding a team who will stick around long enough to release your game.
6) Billing. While this is probably one of the easier parts, your going to need to set up a company bank account, some form of online transaction system, billing support, and keep legally required information on a daily basis otherwise your going to be taken to court before you can hot potatoes!
7) Customer Service. If you've got this far, hats off to you! But now you need a large number of staff to support your customers in all of the bugs, game issues, complaints and other unhelpful drivel they will phone you for. This also costs money, your not going to be able to get a large support team without paying people, and you need this team before you release your game, so no profit shares!
As some have pointed out, this list could go on forever, i think i've made my point now. Please just make something small, fun and unique!
Please dont take this thread the wrong way, this same trend happens on all of the game development websites. I'm simply trying to tell you that you'd be 1,000,000 times better off spending your time developing a game with 2-3 other people over a few months, something small and fun. Sell it if you wish, and then perhaps you might be a tiny little way onto becoming ready to tackle an MMO, if companies like Funcom are struggling with Age of Conan, you've not got much chance.
If you still persist on making an MMO with UDK, then good luck to you. I hope you find great fortune with your MMO, and you'll make yourself and Epic extremely rich.