Not provably fair at all to me. You just prove you don't change the prizes positions after the game starts, but that does not prevent you to win the pot whenever you decide (you know where it is).
Provably fair means you cannot influence the result (even towards yourself), it's not the case here.
Example: whenever half of the spots have been chosen and the pot not found yet, you fake playing like a normal player and win the pot (you know where it is). You win 50% of highest possible pot at that time, and that will happen half of the time (probability to reach half of the spots without the pot being discovered is 0.5).
Rest of the time, a "normal" player will win before half of the spots are chosen.
That is: you earn (0.5 * MAX_WIN), 50% of the games. And you lose less than (0.5 * MAX_WIN), the other 50% of the game.
=> You win overall (additionally to potential house hedge) and nobody can notice anything.
This is just an example, but your hidden edge can be made arbitrarily high, so in theory you can give yourself an house edge of say, 80%, without nobody being able to tell.
I agree, but as far as I can tell there's nothing I can do to prove it. I'm an entrepreneur, the idea was to create something different, a new game concept (all are focus in satoshidice's clones). I understand your concern, but is a limitation since the nature of the game.