Doomsday Lemmings
Doomsday Lemmings is a pack of 21 levels based on NeoLemmix, all of which contain zombies.

Although it starts very easy, the difficulty begins to noticably increase before even the first rank is over. Due to this, and the fact that the zombies act somewhat like moving traps that turn lemmings into even more moving traps, this pack is not recommended for beginners.

        Download Doomsday Lemmings (Version 2.02)
        Requires NeoLemmix Engine V10.12.XX or higher

Doomsday Lemmings consists of three ranks of 7 levels each.

Outbreak
Outbreak is the easy(ish) rank. All of the levels here are quite short, and are medium difficulty at worst.

Plague
Plague is a bit harder. Although the levels remain fairly short, they get harder here.

Apocalypse
The ultimate in zombie lemming insanity; Apocalypse levels are even harder than Plague, and some of them are also quite long compared to the earlier ranks. This rank is not for the Timid among us!