Nice work! But I think you're missing out the most interesting part, in a game of X how much can this exploit raise the house?


Also regarding the exploit, this type of attack was first noticed a while ago (although in the context of bustabit):
https://bitcointalk.org/index.php?topic=709185.msg8535291#msg8535291 who was able to raise the house edge by 0.2%.

Anyway, I ended up solving by mixing in the hash of a yet-unmined bitcoin
block (see: https://www.bustabit.com/faq#fair).