The JROK conversion you link was quite straight forward as CPU2 in Sky Kid Deluxe doesn't do anything really so was simple to remap. In Ishtar it does a lot more and would require a lot more remap work.
Remapping a game is usually not that difficult but it can take a considerable amount of time depending on how the game has been programmed. It is always much easier if the mapping is handled by a PAL/GAL as this can then be modified and is much simpler.
Presume you realise that Tower of Druaga is not a Namco86 board but a Mappy board. Same rules apply for remapping as above.
Remapping is generally simpler than adding Freeplay as detailed code flow does not need to be studied but it can take considerably longer as it can be a time intensive task to catch all address changes.
Remapping a game is usually not that difficult but it can take a considerable amount of time depending on how the game has been programmed. It is always much easier if the mapping is handled by a PAL/GAL as this can then be modified and is much simpler.
Presume you realise that Tower of Druaga is not a Namco86 board but a Mappy board. Same rules apply for remapping as above.
Remapping is generally simpler than adding Freeplay as detailed code flow does not need to be studied but it can take considerably longer as it can be a time intensive task to catch all address changes.
