jeez you guys are way too hung up on all that. and all i said was it seems less likely they would do all that. sure you could take the name of your pet gerbil and hash it a quintillion times and maybe end up with shakespeare, like a room full of monkeys given infinity to jerk around on a typewriter. of course you would then need to encode instructions on all these irregularly sized things and the steps and number of times to hash them and all that in the painting. again, it simply seems less likely. not impossible
no, no additional instructions are necessary, at least when compared with a random private key setup.
You could, for instance,
1. have the following constraint for the private key: every second bit follows the pattern 011.
2. Then, you could have a constraint for the public address: it starts with 1FLAMEN6
3. (any other constraints we are not aware of at present too)
4. then, you generate matching pair of public address and private key.
5. then, you publicly disclose the address and encode the private key in the flames or generally in the picture
6. And you public the picture as a puzzle.
Observe, that this scheme needs no additional instructions over the scheme with a random private key.
EDIT: you see, the pattern in the flames discloses the order on how to read flames, so maybe it was important for the creators to have this constraint and beneficial over random private key. I mean, it is a random private key which would require additional instructions on how to order segments.