This page provides help for those trying to get the Lemmings games to run correctly.
I have personally been able to get all DOS versions of Lemmings running under Windows 95, however I have had more trouble with Windows 98. It may be possible to get them all working under W98 as well, but I haven't tried that hard.
The first thing to try when trying to run DOS Lemmings under W95 is to run them in a DOS box. First, create a shortcut to the exe file for the game you are trying to run. Next, right click on the shortcut and select properties. Click on the "program" tab and click the "advanced" button. Check the box next to "Prevent DOS programs from detecting Windows." Go into the "memory" and make sure everything is set to auto. Then select the "screen" tab and check the box to run the program in full screen mode. With those settings you should be able to run a lot of the Lemmings games (and a lot of other DOS programs as well). If that doesn't work, the next thing to try is running the computer in DOS-only mode. Often the config.sys and autoexec.bat files will need to be modified to get the games to work. I will have more specific information about things that need to be added to those files on this page soon. In the meantime, check this page for help.
With the release of Windows XP, Microsoft mostly broke DOS backwards compatibility. As expected, all of the versions of Lemmings made for Windows work fine under XP, however running DOS versions of Lemmings with XP's native DOS support rarely works. Fortunately, a wonderful little program called DOSBox has been made available. You can get the latest version at the DOSBox home page here. DOSbox is a DOS emulator avaialbe for several platforms, including Windows, Mac and Linux. Using DOSBox requires a basic knowledge of DOS, but is easy to use. Watch for a complete tutorial on running Lemmings under DOSBox soon. Another useful program is VDMSound. You can download VDMSound here: http://ntvdm.cjb.net/. Instructions are included with the program, but can also be found on this page: Running DOS Games On Windows XP (the instructions included with the program are more complete). I had no trouble getting 3D Lemmings to work with that program, however the Original Lemmings still doesn't work right with sound. I still don't know if Lemmings Chronicles will work. I couldn't get it to run even with VDMSound, but I think it's because of a problem unrelated to sound. I have yet to try Lemmings 2: The Tribes. I'll continue to post more information as it becomes available. If you have information regarding getting Lemmings games to run in Windows XP, please email me.
Unfortunately, I don't have a copy of Lemmings for Mac, so I can't help with running Lemmings on Mac. Also, Lemmings for Mac is fairly scarce and expensive. A cheaper alternative to Lemmings for Mac at this point is to use Dosbox to run the DOS versions of Lemmings under Mac OS X (this is how I play Lemmings at this point). You'll need a fast machine to run Dosbox well. I use a Powerbook G4 1.33 GHz, and I get reasonably good emulation speed as long as I set the frameskip to around 5. If you have any information about running the Mac version of Lemmings under Mac OS X, please email me. I'm assuming it will work fine in Classic, but having not tested it myself, I don't know.