I haven't tried running them since I bought them.
The *look* was virtually identical, but I didn't think that they were simply running them in an emulator - too many hardware oddities going on (especially CD-ROM timing and so on).
It is more likely that they are emulating portions of the code (ie. anything at the assembler level), but replacing big pieces of hardware functionality (and system card code) with PC-based software routines.
For example, why deal with CDROM overlays for code if you can afford to load all the code into memory at the same time ? The audio tracks are almost certainly WAV files, and the ADPCM might as well be re-encoded in a more PC-friendly format. Surely there is a better format for backup memory than the PC Engine... (and so on)
Looking at the filesystem on the disc (Xanadu 1) to validate this speculation, I see:
There's some install stuff in the root directory and a subdirectory called "KAZEDEN".
In "KAZEDEN":
- a subdirectory called "FULLWAV" contains about 545MB of WAV files, names after the original audio tracks. "DATA001" plays the CD warning in Japanese, so these are direct rips.
- a subdirectory called "MINIWAV" conatins 24MB of the same files, but in very low quality (8-bit ?)
- a subdirectory called "MANUAL" contains a PDF of a manual for the Windows version (including install instructions), formatted roughly for a DVD case. It's 60 pages and borrows from the original manual and it looks like additional places (for example, there are floor layouts from B1F to 31F of a tower of some sort).
The KAZEDEN directory itself contains just 5 files:
- CORE.DLL (200KB),
- DATA002.REC (28MB) -> this has no CDROM header, so it's not a direct rip, but could be a stripped or re-arranged version of the original data track. The first 0xdcb0 bytes appear to be a jump table in 32-bit format.
- GAME.DAT (11MB) -> this looks like a stripped CDROM header, with "44 41 54 41 0B 01 00 80 00" as the first 16 bytes (the entry addresses and where to load sectors of code), followed by other code bits.
- KAZEDEN.EXE (372KB)
- MAIN.EXE (168KB)
Checking on DATA002.REC, the actual size is 28,030,695 bytes. My Track02 rip from the PCE disc is 28,919,808 (but that includes a lot of empty zeroes at the end...)
So yeah, interesting conundrum. Mostly emulated, but not entirely.
-Dave