I know this is an old thread but anyway.
In short the GOG version of FarCry is 32bit only, not 64bit.
Aliasalpha: I forgot to answer this part, I'm running it flawlessly on 64bit vista ultimate &did nothing but install the GOG version of the game so I'd say the patch is there
Just because it's working on a 64bit system doesn't mean the 64bit patch has been applied. Pretty much all Win 32bit applications run fine on a Windows 64bit operating system.
Also the following from Grah (GOG.com Team) indicates that it is the 32bit version of the game, since v1.4 of FarCry is for 32bit only as stated in the changelog for FarCry patch v1.4. As far as I remember FarCry 64bit is only with v1.32.
Grah: Hi there
The game was fully tested on 64bit Vista, so I can assume it's working fine with that system :) Game is patched to latest official patch which is 1.4.
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Best
Grah
Though a sure way to check if it's 32 or 64 bit, on a 64bit version of Windows. Start the game then open the Windows Task Manager and check the Processes tab for FarCry.exe, if it has *32 next to it then it's only 32bit, if not then it's a native 64bit application.
If you're on a 32bit version of Windows running a 64bit application simply won't work. Though FarCry 64bit should have a folder called "Bin64" in the game folder with the 64bit exe inside, if that isn't there then it's only the 32bit version and it's using the exe in the "Bin32" folder.
Unless you're able to apply the old v1.32 64bit patch to the GOG version you're pretty much stuck with a GOG 32bit version which means you won't have things like...
With it, you can now enjoy Far Cry with additional content, higher frame rates, enhanced textures, longer view distances, and more objects with real-time physics.
I know the FCAM mod has better textures included so that could help improve the 32bit version, but I don't know if it includes the other benefits of the 64bit version of the game.
Fortunately FarCry is an old game so a 32bit system should be able to handle almost anything FarCry will throw at it, the only real benefit to 64bit games is potentially having access to more memory (RAM) as a 32bit system can only handle 4GB of memory (this includes both system RAM and graphics card RAM), if you have more than 4GB installed it won't be used. However many 32bit applications won't be able to use all the memory unless they're Large Address Aware (LBA), you could use something to make the 32bit FarCry.exe LBA so it can access more memory.