No-loss prize games are pools of funds whose accrued interest is distributed as prizes.
The high level protocol architecture is outlined below. The code is available on Github.
Users deposit funds into a Prize Pool. They receive "ticket" tokens in exchange.
The funds earn interest.
The interest is distributed by the Prize Strategy as ticket tokens.
Users withdraw their funds by redeeming their ticket tokens
Prize Pools are the central building block of prize games. They pool user funds in a yield source and expose the yield to a Prize Strategy, which then disburses as it pleases.
Prize Pools can be differentiated in four primary ways:
The yield source the prize pool uses to generate no loss return
The prize strategy used to determine frequency and distribution
The rewards offered by the prize pool
The asset type the prize pool accepts for deposits
Prize Strategies determine the prize distribution for the Prize Pool. They can define any logic to allocate tokens that the prize pool accrues. Specifically they can:
Award yield in the Prize Pool as pool tokens
Award ERC20 tokens held by the Prize Pool
Award ERC721 tokens held by the Prize Pool
Yield sources take deposits and generate interest for the prize pool. Yield sources must be designed to be no-loss, and adhere to the Yield Source Interface.
Fixed point math is used extensively in PoolTogether. We used fixed point math with 18 decimal places for all fractional numbers. You can think of this as being just like Ether and wei: a value of "1" Ether is represented as "1000000000000000000" wei.
When a number is a fixed point 18 number we always suffix the number with mantissa. For example the credit rate is written as creditRateMantissa, because it is a fixed point number.
PoolTogether is conscious that to become a truly lossless prize protocol the transaction fees involved must be minimal. The current design utilizes the Minimal Proxy Factory design where possible to reduce gas usage.
Note that these fees are paid to the Ethereum Network and not to PoolTogether. The amount a transaction costs in USD is calculated as: the amount of gas used * gasPrice * USD/ETH.
Here is a list of common actions and their costs:
Estimated Gas Cost
$USD (40 GWei, $600/ETH)
Creating Pools with the Builder
Entering and Leaving Pools
RNG request - Chainlink VRF
20 (@ 10 USD/LINK)