one of the core values of the game is that, due to the decentralized nature of the pools and miners, the outcome cannot be manipulated. If you have a specific scenario in mind, I’d love to discuss it further 
1. A large miner can rig this by moving to a different mining pool to change the chance of winning. 2. How is the block time determined? Maybe a mining pool can rig the block time.
Thank you Knight Hider. Let's go with option 1 for manipulating.
Let's say an extremely large miner, who has 1% of the total network, decides to manipulate the market and switch off from the current mining pool to a different one just because of BlocksRace game. First such kind of switch is costly for him, as it is not instant, and he risks block to be mined during it. The risk for him is around 1% of 300K USD = 30K USD . And even if block is not found during the switch, the whole manipulation just increases by 1% the chance of his new mining pool to get the block. Moreover for the version we are preparing for integration with different casinos, we will have realtime data from the mining pools what is their current hashrate so this change will be reflected as well with a reduction of the odds for this pool.
Option 2 - mining pool can not rig block time as this is race between all mining pools which one will compute/guess a hash(with the pending bitcoin transactions as input) , lower than the current bitcoin network difficulty. Leaving this from one of the prominent cypherpunks in the space
In regards of current option for betting & payout, I do not want to argue, it is not something that can be scaled up for sure, thus for the next version we will offer you the option to make a bet & withdrawal through Lightning .
Let us know all of you what you think if such a kind of option will make it easier to make bets or you prefer to have my account section with deposit & withdrawal options with different cryptocurrencies