This for building a small lottery game accepting bitcoin as a payment
It shouldnt be a static one, odds or winning chance should vary on how much ticket you have bought in just like on what most lottery sites do apply on.Take this as an example: https://crypto.games/lottery/bitcoin
Lastly, it doesnt have any house edge.
Hope you do get some idea on what i have shown.
Yes it's quite a good game, but the winning chances increase only if I buy more tickets let's say if I buy 6 tickets I will get a chance of 28% to win, but in our game every winning ticket will have minimum odds of 3 and with zero house edge