so as you said there is this random number generator,
it uses two different input to generate the random number that is used in the algorithm to generate crash result
first input -it's like server seed- is a HASH string that is decided when crash first released
second input -it's the client seed- is hash of the future bitcoin block so players know that it's not chosen by the house
first input (server seed) is updated when a new bitcoin block is mined (so when client seed is changed)
update uses the HASH string (current server seed) itself to hash itself so it's not random and based on the predetermined hash at the release of the game
also explained here: bitcointalk.org/index.php?topic=5162888.0
