Level Codes
Level 1 - LDKD
Level 2 - HTDC
Level 3 - CLLD
Level 4 - LBKG
Level 5 - XDDJ
Level 6 - FXLC
Level 7 - KRFK
Level 8 - KLFB
Level 9 - DDRX
Level 10 - HRTB
Level 11 - BRTD
Level 12 - TFBB
Level 13 - TXHF
Level 14 - CKJL
Level 15 - LFCK

Secret message
Load the "FILE0146" file as a GIF picture with a graphics program.