Oregon Trail, Storybook Weaver and PUTT PUTT are exe thingies, you know.
Many files from Abandonware (if not all) are meant for DOS/Windows operating systems.
For those you are barking underneath the wrong tree.
For playing them in Vista, I would suggest to set up DOSBox or Oracle´s Virtual Box.
Old Windows flavours can be set up in Virtual Box, some pre-built images of Windows are floating around too.
Usually it is specified which OS was needed to play each and every game. With some luck, you´ll aquire a suitable runtime evironment for your findings, but that will not be a Mac, I´m afraid.

Here are at least
spectre http://www.mediafire.com/?v4j7r9dj2kud6z6
Backyard http://www.mediafire.com/?h777f8v5he41683
Decompress with 7Zip and mount with the BII GUI. There are images inside, that can be opnened with DC6 from its menu - no double clicking. I did not look closer, probably game installers, you´ll be on your own with that.

Edit: Yep, there is something wrong with the images. Some are not preserved well in the cloud.
Maybe I can fix that...

Use Disk Copy with the .dsk-files. Files ending in .dsk usually are copies/images of diskettes. Seems someone collected floppy images in a .img-file which means it becomes a bit like a Russian doll

for everybody who wants a nice and easy setup im uploading on maxzzz's server "upload/emulators uploads/devils_advisor/" a ready to use package with system and games and apps. see the filelist to find out what you get. there are even pictures for the setup part. for the windows user dl the newest sheepshaver executable and replace it. you should be able to reuse the prefs file. im still uploading it is a lot of stuff but like i said ready to use once you got it unpacked. i had to go this way because some of the files are to big for a free account on mediafire or rapid.

Updated the MF links, hoping things will work this time.
This is how the volumes should look like, when mounted with BII:

I recall some weird sounds and other "features" with software running in virtual machines too.
Remember that all hardware has to be rebuilt by the VM on the fly. A RAM and CPU eating procrdure.

@Bootbie: That Storybook Weaver that you linked above at Mediafire is an old DOS only game. It won't run on Basilisk II

From the readme:

To run Storybook Weaver, you need an IBM(r)/Tandy(r) or compatible with
DOS 3.3 or higher and 640K or RAM. You also need a VGA or MCGA graphics
card, a 256-color monitor, and a hard disk. A mouse is highly recommended.

Storybook Weaver supports AdLib(r), Sound Blaster(r), and compatible sound
boards.

For printing, Storybook Weaver supports Epson(r) Series, IBM Proprinter(r)
Series, IBM Laserprinter(r) Series, Tandy DMP, HP LaserJet(tm) Series II and
III, and most monochrome and color 9-pin and 24-pin dot matrix graphic
printers, inkjet printers, and laser printers.

This is very old pre-Windows 95 software (1992) and is not Macintosh compatible.

[Also]: Looking at those Spectre screenshots (yours and 24bits) whoever made that ".img" has made a mistake building this ".img" - It is not going to work for you as is.

They've unzipped a ".zip" and converted the unzipped folder to a ".img" file. But, the ".zip" they had extracted, was created using MacZip (available at the garden). You can tell this because it creates a proprietary MacZip content in the file containing the resource forks of the Mac files within the zip in a folder named ".XtraStuf.mac" (visible in both screenshots).

The original zip file needed to be unzipped with MacZip (on a Mac) to unzip the file correctly.