Public Server MMOs

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Public Server MMOs
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Public Server MMO

• Whats an MMO?
• Massively Multiplayer Online game
• Persistent world
• Success stories
• Lineage
• World of Warcraft

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MMO

• MMO problems
• Huge scalability issues
• Hosting costs 20 of subscription revenue
• Support costs 20 of subscription revenue
• Content costs Unknown but surely large
• Those are for successful MMOs
• Unsuccessful ones have the cost of failure

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Public Server

• Whats a public server game?
• Game company distributes the server code
• Users host the machines themselves
• Users can modify the server
• Examples
• Half-life, Counter-Strike, Doom
• Neverwinter Nights
• Benefits
• User hosting resources are extremely plentiful!
• User content creation extremely plentiful
• Drawback
• No subscription model
• No persistent world

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Public Server resources are plentiful
70 of all servers are empty
CDF of fullness of Counter-strike servers
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Public Server content is plentiful
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Our Goal Public Server MMO

• Decrease hosting and support costs by not hosting
  gameplay
• Decrease development costs by allowing
  user-generated content
• Allow for a persistent world with public servers

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Basic Architecture

• Public Servers host game play
• Publisher hosts authentication, billing, loot
  server
• Users store persistent data themselves
• Key challenges
• Authentication
• Persistent Content across public servers
• Trading Items

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Public Server MMO Participants
Loot
Publisher
Public Server
Client
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Authentication keys

• Clients must be able to authenticate themselves
  to loot server, public servers
• Cli_key_pub, Cli_key_priv
• Clients keep private key
• Loot server must be able to sign loot, as
  authentic
• Loot_key_pub, Loot_key_priv
• Loot server keeps private key
• Loot server must be able to bind loot to specific
  players
• Bindi_key_pub , Bindi_key_priv
• Loot server keeps private keys

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Challenge Persistent Content

• Content creation
• Loot is designed by community and approved by
  publisher
• Loot is issued according to authenticated
  player-minutes to servers
• Servers distribute loot according to game-play
• Content security
• Loot is signed to a player and signed to the loot
  server
• Public servers and other players check a piece of
  loot by checking signatures
• Loot can be stored at the clients
• Caveat loot cannot be traded from players

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Challenge Authenticated Time

• How are player minutes authenticated?
• Public servers want minutes
• Players want minutes
• Use a periodic Reverse Turing test that fits in
  with game-play as a mini-game
• Finding objects in a scene
• Identifying human faces

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Challenge Trading Items

• We would like to relax the loot cannot be
  traded restriction for game-play purposes
• We dont want to allow item duping
• We dont want to keep an item revocation list
• Solution periodic trading window
• Publisher coordinates a player-wide swap meet or
  auction
• During auction, each players goods are re-issued
• Old items are invalidated by changing
  Loot_key_pub, Loot_key_priv

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Trading Illustration
Mint
Player 2
Player 1
Submit items to mint
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Trading Illustration
Mint
Player 2
Player 1
Receive new items
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Quantifiable elements

• Re-minting all items in the world of items vs.
  time
• Generating / verifying CAPTCHAs of captchas
  vs. time

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Conclusion
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scratch

• How can we prevent servers from giving players
  loot for doing nothing
• We dont!
• We do require players to be present at the keys,
  and we assume they will gravitate towards
  compelling content
• Bootstrapping why go to a new server?
• Trickle some loot to a server just for being up

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A
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Server
Game
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