http://store.steampowered.com/app/45400/ = Fortrix
Let's say making new e-mail addresses, and billing info for each Steam account takes 30 minutes total. Buying Fortix and waiting for the Steam servers to upgrade your privileges takes 5 minutes. So about 35 minutes total for each vote. (That is, if Steam doesn't detect you for creating so many accounts).
In order to vote 1000 times, it will cost $1000 and 35000 minutes (600 hours). So it is completely impractical to create new accounts just to vote, if only 1 person is doing it.
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Now say a Blockland user is giving out $1000. Each player can get a max of $10. Players create new e-mail addresses and Steam accounts. Then the Blockland user wires them $1 to buy Fortix. If players pitch in with their own money, it'll be easier to get more accounts and more votes.
So if 1000 players participated in this, then we would get 1k votes. I know it's insignificant, but that's twice the amount of votes there are now.
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If each Blockland player spent $5 and therefore 5 Steam accounts, and 1k users participated, BL would get 5000 votes.
But I'm sure Steam would detect this scandal if it was run by the developers.