1FLAMEN6rq2BqMnkUmsJBqCGWdwgVKcegd is a vanity address. Using a word list is impossible.
This can not be highlighted enough. Every third post is something where people try to solve this using words, not realizing there is 0% chance it can lead to solution. Author of the puzzle couldn't choose anything arbitrary because we have vanity address to start with, the private key is forced to the author and she had to paint it somehow in the picture.
She got a random private key similar to this - 5KTVSQgC3Mx1hBWzFSADwYds4L31nbPSNPRQwE1F2GwDfdUjSZK
I found the vanity address 1FLAMEuWQftZ6moQvbAZo5aTqpPbeCrjZj the above is the private key.
She then encrypted the key using BIP38 and got something similar to this.
6PRN5sGMbcMKzqP1ofE7t4CeMeKmxzSQ6MRfp6cPAGipe1HiF4L9Jf3E2p
This is what is hidden in the flames. Find 6PR and you get the BTC.
It could be in binary in which case you are looking for this string 00110110 01010000 01010010
Hex is 36 50 52. I don't think it is encoded using hex though.
It could be an Base 64 matrix in which case it could be random. You can't brute force that.
I would disagree slightly with this. To illustrate I've generated one more vanity addresses that start with 1FLAME:
Address: 1FLAME9zvyZyE3kMXiTsFcuZNeC4gokabz
Private key (WIF): 5KNTFzU1JwH5dQvPWiRj3dXAoJ9tsSpZmZLaoJNwBfHXGw19g9A
Private key (hex): CCBC2134B2B448250D1B08E77F5AF029F3AC2DEF0BDF253436950AA057216DE4
Private key (binary): 1100110010111100001000010011010010110010101101000100100000100101000011010001101100001000111001110111111101011010111100000010100111110011101011000010110111101111000010111101111100100101001101000011011010010101000010101010000001010111001000010110110111100100
I don't think that the author used private key in WIF format or BIP38 encoded WIF format. It would be easier for her to use private key in hex or binary format. All private keys in hex are 32 bytes long, meaning they have 64 hex digits [0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F], or 256 binary digits [0,1].
If you ask me how she could have encoded these in the picture, maybe there is something in what Regisek hinted few posts above, she used the hex or binary digits as indexes to the chessboard, Regisek nicely noticed size of the chessboard on the picture is 7 x 9 fields, and 7+9=16, exactly as number of digits in hex encoded private key. I'll try to illustrate it like this:
How exactly can flames be used as indexes is anyone's guess.