I must be dense or blind. I just got Myst IV. It came on 2 DVDs labelled "PC - MAC" with OS X and QT logos on them. However, when I look at the content, I see only Windows files. I saw people mentioning "MystIV_Setup.app" as the installer program. There is no such a file there, neither on disk 1 nor 2. ???

The disc you should have in your drive will display the icon text "Myst4_1". The only content of this disc is "MystIV_Setup.app". Are you sure you have inserted the correct disc?

The disc label displays "WIN MAC DVD-ROM." If you look under the "T" for Teen rating, there is a number: 681632-DVD1.

I presume you are on a Mac. Your Mac's disc drive does read DVDs, not just CD-ROMs, right? What is your operating system version?

I tried it on three different Macs, from indigo iMac (upgraded to DVD-ROM drive) running Panther, PowerBook G4, and brand new dual-core iMac running Tiger. The mounted volume is named "Myst4_1" alright. The version I got is for the German market, so there is no T-rating on the label, but there were only 2 DVDs in the package, Disk 1 and Disk 2, both labelled PC-Mac, just like the packaging and installation instructions. However, all I ever see are Windows installation files:

autorun.inf
common
data1.cab
data1.hdr
data2.cab
dvd.id
engine32.cab
layout.bin
patch
set100.exe
Setup.bmp
Setup.exe
setup.ibt
setup.ini
setup.inx
setup.skin
setupdir
win32

I suspect that this is one of those dual-partition DVDs which should mount a different partition depending on the operating system, but for some reason, mine mounts Windows not Mac partition.

Have you tried inserting Disc 1 into the drive and double-clicking on setup.exe on the DVD?

Yes, I have actually tried that. No surprise: no application known to open that file. What I see is definitely a Windows installation. I guess the question is really if there is a trick to get to Mac partition or do I need to get a new set of DVDs from ubisoft. Unfortunately, we didn't buy the program ourselves.

No tricks on the U.S. version of the game, and I cannot see any Windows files on my Myst4-1 DVD. Just the MystIV-Setup.app file. So I would guess that you need another DVD set. (But I know nothing about the German version...) Have you contacted Ubisoft Support?

I just filed a problem report through their support web site.

While you're waiting for a reply from Ubi support, make certain that both Revelation DVD's are free of smudges, fingerprints, any sort of microfilm/haze coating, etc., that could interfere with disc reads. Some haze coatings are essentially invisible to the naked eye, but not to the drive's lasers.

Don't just look at the discs and say "yeah, clean". Actually clean them using either water-clear (additive-free, no witch hazel or whatever, no green or blue color) isopropyl alcohol or a warm mild detergent solution. Dry with a soft, lint-free cloth using a center-outward motion, NOT circular around the disc. Remove any scratches deep enough to catch a fingernail using one of the repair kits available locally or from an Internet supplier. Then try installing Revelation.