So a couple of days ago, DaDice added a jackpot feature to their site.
It seems particularly poorly thought out, but it got me thinking...
How *should* a jackpot feature be implemented?
The DaDice jackpot has several flaws:
1) it's not provably fair at all - it depends on both the betid and the time, both of which can be undetectably maniputulated by the site
2) their jackpot has the best edge for the smallest bets; it actively encourages people to make tiny dust bets rather than big bets
3) their jackpot has a huge negative house edge; it is very gameable and unsustainable, unless they intend to cheat (see point 1)
So how can we do it better?
How about:
1) Since we have 6 digit rolls as opposed to their 4 digit rolls, we can get rid of the betid and current time components, and just make it that you need to roll 99.9999 to hit the jackpot. That makes the jackpot a 1-in-a-million chance. We see around 5 million bets per day, and so will see that many jackpot wins per day.
2) Clearly we need to scale the prize according to the amount risked. It's silly to encourage dust bets. And so hitting the jackpot will pay out a share of the prize pool based on the site of the bet. How about if the bet size in CLAMs is the percentage of the prize pool you win. So if you hit the jackpot with a bet of 5 CLAMs, you get 5% of the pool. That way the pool doesn't shrink too fast and gets a chance to build up. The vast majority of bets are dust, and so we can expect most jackpot wins to be bets staking less than 1 CLAM, and so it will be relatively rare that the pot goes down by much.
3) We've promised investors a 1% house edge, and 10% commission. The house will have to fund the jackpot itself since we don't want to change the deal we made with investors. We could initially fund it with 1000 CLAMs, and leave it to stake. Would the staking rewards make up for the payouts it makes? Staking pays out 0.2% per day, and we expect 5 jackpot wins per day. So long as the sum of the stakes of the 5 winning bets is less than 0.2 CLAMs, the pot will increase that day. That's probably usually going to be the case.
Thoughts? Suggestions? How would a well thought out jackpot system work? Is the proposed scheme worth implementing? Are the proposed prizes too small to bother with?