With default settings, Lemmings may not work correctly on many versions of Dosbox, so I’m putting a few notes here to help anyone get it running correctly.
The first issue is that you may notice strangely garbled or corrupted looking colors on some screens. To address this, you can change Dosbox’s machine type in the config file from the default “svga_s3” to “vgaonly”. Alternatively, you can also Try Dosbox-X, which has more accurate video emulation and should work correctly under all settings.
The second issue you may encounter is that Adlib music does not play at all, leaving only PC speaker effects. This happens if the emulated cycle count is too high. A setting below 10,000 or so should resolve the issue and run the game perfectly fine. It varies by Dosbox version, so if it still doesn’t work, just keep lowering it until it does.
Finally, even with the music working, you may notice that after restarting a level, the music track resets to the first level’s song. This is actually a bug in the game itself and has been patched by a community member. The problem is detailed in this thread on lemmingsforums.net. Simply download the L1-music-patch.zip file attached in the thread and follow the readme instructions within to patch the game.
Feel free to ask in this thread if you’re having any other issues getting the game to work correctly.