Adding my two cents here about the lottery: They designed it in a way that they cannot cheat the winning index, that's good, but it's still not provably fair because they could dilute the lottery tickets as much as they want with bogus users (The lottery ticket list could be diluted). Not saying they are cheating the lottery, but lottery is not provably fair for that reason - it would be very hard to make it provably fair, short of something like an audit that's nearly as hard as auditing an exchange. I do automated multiply bets with validation for small amounts and haven't noticed any server seed changing. Not tracking free rolls.