the .mdl and .ini files go together and as far as I know the .mdl should be for a sprite such as "cleanerbot01.mdl" which is paired with the "cleanerbot01.ini", I can read the .ini files and it tells the .mdl what the sprite should do as expected of an .ini, but so far I haven't found any program that can read the .mdl files, and in a normal text editor its shown as what appears to be encrypted text and binary text and I can't get anything to read it.
it seems as though the .ptb is used in the game as information for what layers tiles should be on, as they are listed "ep01lvl01.ptb", "ep01lvl01bg01.ptb", "ep01lvl01bg02.ptb", and "ep01lvl01Fg01.ptb", and is in the same folder with the .tiles files, its possible they could be audio related, but the music/ sound effects are generally .wav files so it seems unlikely. and the .tiles files are also not reading in most utilities as they come out as encrypted or binary as well.