5 Reel 20 Line TX based slot machine. Dice style instant returns. up to 83x bet.

[drakahn]

Part two of me learning bitcoin is a (dice style) slot machine

http://drakpot.nzcloudhosting.com/slots/index.php

1 Line  :      1SLoTSDphRovRaQqw4BNxU4sVb2biXYyg   
3 Lines :      1SLoTSLKsnsb8Ba2XrRHeJWepRxYh9His
5 Lines :      1SLoTSqPptYR4ecSmUbuzwq4xywREKE3s
10 Lines:      1SLoTScYvE2v8So9jTjmCXa9gg4RvC2k8
15 Lines:      1SLoTShthHPJVjT6R3uYUnKc3S2ooQjBB
20 Lines:      1SLoTSPXDRdubbuYtuZhwyb9ihkkfadrc   

How it works:
Send any amount between the min and max bets to the address matching the number of lines you wish to play, the "reels" are worked out based on the transaction hash

Prizes are as follows:
Three Matching = 7 x (bet/lines)
Four Matching = 28 x (bet/lines)
Five Matching = 83 x (bet/lines)
All lines pay left to right

IMPORTANT NOTICE: prize payments only go to the same address as paid for the ticket, you should be sure to only use a wallet you know will send coins from an address you control.

Send any amount between 0.001 and 0.20 to the address matching how many lines you want to play, you will receive a payment shortly after to let you know how it went

After betting you can check your spin by entering the txid on the side of the website.

This is the first time its 'in the wild' so it could be shutdown at any time if a problem is found
bets outside of the min/max range will be refunded minus tx fee


This shares only a name and hosting with the drakpot lottery, it is a separate game with a separate wallet.

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[drakahn]

I've added recent spins and a bit more of an explanation on how it works, I'm working on it so that I can start releasing old secrets soon

[darkmule]

This seems to have won:
05af9b3a9bea13bec3cbe7b93e0521ae0df8b2e38e5df503b08b35fa08840d49

This paid four of a kind on three lines.

I haven't seen anything back yet, and it's hours later.

Incidentally, I've never had problems getting the 0.00000001 BTC for a losing bet.  For example, here's one:
58e5d941521372fa2e337231809819ddb10c60160a1060d9099b77a27a0a0024

[drakahn]

I am away from home right now so can't see exactly what went wrong, but I can see that you sent a bet above the maximum 0.20 btc bet, so it was flagged for a refund, but for some reason the refund went to the wrong address, I don't have access to anything from here to fix it now though, so until i can get home and see what went wrong refunds for outside of range bets will be delayed

[darkmule]

Thanks for pointing that out.  I'd misread this section of the first post:

Max bet is set on 0.05 per line played until I'm sure everything is as it should be.

Send any amount between 0.001 and 0.20 to the address matching how many lines you want to play, you will receive a payment shortly after to let you know how it went

I'd thought .05 per line X 20 was a possible bet, and missed that the next line sets a hard limit on the total bet.

[darkmule]

Whatever caused the BTC to be returned to the incorrect address, it has now (I assume manually) been fixed.  Thank you.

[dooglus]

http://drakpot.nzcloudhosting.com/slots/index.php

The Algorithm:
Reels are the hash of the txid+secret sorted top to bottom, left to right.

Is that right?  Is there any sorting going on?

I'd have thought that you simply take the first (or last?) 15 hex characters of hash(txid+secret) in their original (unsorted) order to get the colours of the 15 symbols.

Also, I'm a little confused about the payouts.  The rules state:



but here's an example winning line:



That's "5 matching" isn't it?  So it should pay out FIFTY times bet/line?  Bet was 1 bit cent, lines was 10, so it should pay out 5 bitcents, no?  Maybe I'm getting it wrong somehow.  (Edit: I was mixing up the two recent 10 line winners.  This guy bet 0.001 so the payment is correct.  But it should still say "FIFTY TIMES" not "FIVE TIMES" in my opinion).

Finally, I'm confused about what "three matching" means.  I would have thought that this is a winning line, because it has 3 the same colour:



but it's a losing line.  What does "three matching" mean?  Do the first three colours have to match each other?  "all lines pay left to right" is maybe a hint, but I didn't understand what that meant either.  Is that saying that "three matching" only applies to the first 3 colours on each line?

Edit: oh, also it would be better if both the main page (where it shows recent bets) and the "check txid" page showed the amount bet, and the amount bet per line.  I know I can look it up in the blockchain, but why not show it on the page too.

[dooglus]

I just worked out the house edge, given my current understanding of how the payouts work:

Code:

>>> (1*50 + 3*20 + 12*10 + 240*0) / 256.0
0.8984375

You're paying out 89.8% of received bets, and keeping 10.2% as your house edge, is that right?

[drakahn]

It is the first 15 characters of hash(txid+secret), sorted top to bottom, Left to right, so
1.4.7.10.13
2.5.8.11.14
3.6.9.12.15

To win the matching characters must be the first in the line, left to right

Thank you for pointing out parts that are hard to understand and I have added the bet amount to the page.

I sent you a PM about the math

[dooglus]

It is the first 15 characters of hash(txid+secret), sorted top to bottom, Left to right, so
1.4.7.10.13
2.5.8.11.14
3.6.9.12.15

To win the matching characters must be the first in the line, left to right

Thank you for pointing out parts that are hard to understand and I have added the bet amount to the page.

I sent you a PM about the math

I think I'd call that something other than "sorted".  Sorting is taking things which are out of order and ordering them.  You're not doing that.

I answered your PM and look forward to playing the game if the house edge is reduced as a result. 

[drakahn]

Payouts have been adjusted to have an expected house edge of 1.95%

And some other cosmetic/grammar changes

[dooglus]

Payouts have been adjusted to have an expected house edge of 1.95%

And some other cosmetic/grammar changes

Good!

One other comment: the logo seems to me to be horribly ugly and very hard to read.  I'm not usually sensitive to such things, so I think it must be unusually bad.

[dooglus]

How about a link on each of the 'recent spins' entries which takes me to the page for that spin, so I can see the reels and payouts?  Currently I have to copy, paste, and edit the URL of the txid link into the 'check txid' box, which is kind of awkward.

I just added up the bets and payouts of all the displayed 'recent spins':

From 95 displayed recent spins, a total of 4.10929972 was bet, and 1.89070043 was paid out.  That's a return to player of just 46%!  I guess people have just been unlucky so far.

[dooglus]

I tried the game out.  I sent 1 bitcent and played 20 lines.  3 of them got 3-in-a-row, giving 3*7 = 21 twentieths of a bitcent.  And the transaction fee (1/20th of a bitcent) took the prize down to 20 twentieths of a bitcent - exactly what I paid.

I'm sure it must mean something - as far as I've seen nobody ever won back exactly what they sent before.

And if I hadn't complained about the house edge being too high, I would have made a profit, because 3-in-a-row used to pay 10x instead of 7x.  (I complained in PM that 3-in-a-row was paying proportionally more than it should compared to the rarer 4- and 5-in-a-row payouts.  So they got fixed...

[dooglus]

I just noticed - you accepted my bet with 0 confirmations, and paid out my winnings without using my bet as one of the inputs.  That probably opens you up to fraud.  I can double-spend all my bets to you and you'll probably still pay out my winning bets.

It's safer if you can make the payouts depend on the bets - so if the bet never confirms neither does the payout.