Oh No! More Lemmings was the first additional level pack to the original Lemmings and was released on only a few systems. This level pack included 100 single-player levels and where available, 20 two-player levels.

The single-player levels are separated into five difficulty levels: Tame, Crazy, Wild, Wicked and Havoc. The level styles are all different from the original Lemmings, as is all the background music. Aside from this, the gameplay and game engine are exactly the same as that of the original game, hence making this a level pack rather than an actual sequel. The game does not, however, require the original to work.

After ONM Lemmings, additional level packs were released around the end of each year. In the UK they were known as "Christmas" or "X-Mas" Lemmings, in the US they're called "Holiday" Lemmings. All levels have a snowy level style and Lemmings wearing little Santa suits, but the gameplay of the original game remains exactly the same. Each level pack (there were ones for 1991 through 1994) contains only a handful of levels, though most packs were freely available to people when originally released.