CoinTricks #1: Block Darts, Round Two - only 0.1 BTC (hit #133119)

[cecil w.]

** (The carnival is closed until Monday.) **

Here's a new game. Darts, using only the Bitcoin protocol. (Anyone done this before??)

How to Play
In this game, the bullseye is the end of a specific Bitcoin block. The dartboard is a bitcoin address.

Everyone uses their Bitcoin client to attempt to "hit" that block.

The bottom of the Bitcoin client shows what block you're on:

http://i.imm.io/6MMp.png

So, say, for example, we selected block 133082 as the target. When it says "133081 blocks" there, that means block 133081 is finished on the network. So now you send your bid to the address of the dartboard, hoping to hit the last part of the next block: 133082. It's all about guessing when the network is going to finish that block. Sometimes a block is done in fifteen minutes. Other times it's three minutes. No one knows!

If you miss block 133082 (by being too early or too late), then your bid goes into the pot. Keep in mind that some blocks are extremely short and only contain one transaction!

Darts are scored in the order they appear on blockexplorer. Game is tallied after 2 confirmations (the target block and the block after that.)

About the CoinTricks series
I'm more interested in the protocol hacks that make these games possible, so I don't charge any fees for this game. I have a few other games I've designed which are more complex, depending on how this one does.

SECOND ROUND: TIP OF THE TAIL.
This time, we're shooting for the end of the block.

In this round, everyone bids 0.1 BTC. Anything above or below will be returned. The bottom half of those who hit the block all win.

The winner takes half the pot. Second place takes half of what remains. Third, half of that. Until the top half is paid. The last person gets what's left, minus transaction fees.

If there is an uneven number of players, the middle player is still in the winner's circle. (This way two will win if only three hit.)

If there is only one winner, this person counts as 2nd, 3rd, 4th, etc. Meaning the pot is theirs.

No winners and I'll return your tenths of a coin.

TIPS
Send from the Bitcoin client! Do not send from a website. I will use your return address to send back the winnings.

Start up the client at least five or six blocks in advance. Your client needs to be up-to-date with the blockchain!

Also: donation bids. If you like what I'm doing with these games, send a bid of 0.09 BTC instead of 0.1 BTC. I will chip in the extra 0.01 BTC and, if you win, 20% of your return will go toward my project 'coinsplit'. I need some real BTC to test with and to do some coinsplitting games with.
http://forum.bitcoin.org/index.php?topic=20252.0

ARCHIVES
Round one: EVEN STEVEN. BLOCK #133100.
(Goal was to hit the beginning of the block.)
https://spreadsheets1.google.com/spreadsheet/ccc?hl=en_US&hl=en_US&key=tMQnAnDW616MXLuZk9En5Kg&authkey=CI_W-Y4F#gid=0

Round two: TIP OF THE TAIL. BLOCK #133119.
(Goal is to hit the end of the block.)
https://spreadsheets1.google.com/spreadsheet/ccc?hl=en_US&hl=en_US&key=tMQnAnDW616MXLuZk9En5Kg&authkey=CI_W-Y4F#gid=1

[cecil w.]

Sorry, let's do block 133100. After looking at block explorer, it could take several days to hit 134000.

[cecil w.]

Six blocks left (about an hour) until this starts.

[cecil w.]

Spreadsheet.
https://spreadsheets1.google.com/spreadsheet/ccc?hl=en_US&hl=en_US&key=tMQnAnDW616MXLuZk9En5Kg&authkey=CI_W-Y4F#gid=0

[cecil w.]

Block 133099. Fire!

[cecil w.]

Round one is done. Thanks!

Next round is at block #133119. (About two hours from now.) See the rules above, they've changed for this round. This one's "tip of the tail". The goal is to hit the end of the block this time, not the beginning.

[cecil w.]

Okay, three blocks away now. (About 15-20 mins.)

Get ready. Update your client. And fire away after it says '133118 blocks' at the bottom.

Remember, we're trying to hit the end of a block, so it's not too late as long as block 133119 hasn't passed. Good luck!

[cecil w.]

Okay, I just saw block 133118. Fire your dart when you feel comfortable. Today blocks have taken anywhere from 18 seconds up to 30 minutes to generate. If you go off the end, you land in the pot!

[bitlotto]

This has got me wondering HOW blocks sort the transactions? Is it all based off of when the miner get's the transactions?

[cecil w.]

So, yeah, the order of transactions in blockexplorer (and in the block itself) isn't chronological. It's valid for them to be rearranged in order to get them to produce a useful hash. So they should end up in a random order.

This means that playing darts is less about timing and more about luck (unless I ordered by receipt, in which case it's ordered first by timing and then by proximity in the network.) You could probably run a lotto doing this without any outside randomization.

Before I run this game again, I think I'm going to run some simulations on the test net, in order to get a feel for good strategies and good variations. I want to do a version that's more like a game with rounds. Where bidders shoot for three consecutive blocks. Or each spaced apart by one block, perhaps.

Thanks for your interest!

[bitlotto]

This means that playing darts is less about timing and more about luck (unless I ordered by receipt, in which case it's ordered first by timing and then by proximity in the network.) You could probably run a lotto doing this without any outside randomization.

Interesting. I don't think it would work though if the jackpots got really big. Once it does it can be assumed that some miners may try to cheat. A miner with a lot of power may try to skew things in their favor.