The goal is to guide at least a certain percentage of the green-haired, blue-robed lemmings from the entrance to the exit by clearing or creating a safe passage through the landscape for the lemmings to use. Unless assigned a special task, each lemming will walk in one direction ignoring any other lemming in its way (except Blockers), falling off any edges and turning around if they hit an obstacle they cannot pass. A lemming can die in a number of ways: falling from a great height, falling into water or lava, disappearing off the top, bottom or side of the level map, being caught in a trap or fire, or being assigned the Bomber skill. Every level has a time limit; if the clock counts down to zero, the level automatically ends.
To successfully complete the level, the player must assign specific skills to certain lemmings. Which skills and how many uses of each are available to the player varies from level to level, and the player must assign the skills carefully to successfully guide the lemmings. There are eight skills that can be assigned: Climbers climb vertically though fall down if they hit an overhang. Floaters use a parachute to fall safely from heights. Bombers explode after a five-second timer, destroying themselves and any destructible landscape in close proximity, though not damaging other lemmings or traps. Blockers stand still and prevent other lemmings from passing; lemmings that hit a Blocker simply reverse direction. Builders build a stairway of 12 steps. Bashers, Miners and Diggers dig horizontally, diagonally downwards or directly downwards respectively.
While the player is able to pause the game to inspect the level and status of the lemmings, skills can only be assigned in real-time. Lemmings are initially released at a rate predetermined by the level (from 1 to 99). The player can increase the rate as desired to a maximum of 99, and later decrease it down to, but not lower than, the initial rate. The player also has the option to "nuke" all the remaining lemmings on the screen, converting them to Bombers. This option can be used to abort a level when in a no-win situation, remove any Blockers that remain after the remaining lemmings have been rescued, or end a level quickly once the required percentage of saved lemmings has been reached.
The four difficulty groups – "Fun", "Tricky", "Taxing" and "Mayhem" – are used to organise the levels to reflect their overall difficulty. This rating reflects several factors, including the number of obstacles the player has to surpass, the limitation on the number of types of skills available to assign, the time limit, the minimum rate of lemming release, and the percentage of lemmings that must be saved. Some versions have additional difficulty ratings with more levels in each.
Two-player mode
The original Lemmings also has 20 two-player levels. This took advantage of the Amiga's ability to support two mice simultaneously, and the Atari's ability to support a mouse and a joystick simultaneously. Each player is presented with their own view of the same map (on a vertically split screen), can only give orders to their own lemmings (green or blue), and had their own base. The goal is to get more lemmings (regardless of colour) into one's own base than the other player. Gameplay cycles through the 20 levels until neither player gets any lemmings home.
Development
Mike Dailly, the first employee of DMA Design and one of the programmers for Lemmings, provided a detailed history of the development of the game entitled "The Lemmings Story" in 2006. David Jones, founder of DMA Design, has also commented on the development and success of Lemmings.
The inspiration for gameplay came as a result of a simple animated character sprite in an 8×8 pixel box created by Dailly using Deluxe Paint as part of development for Walker, then envisioned as a sequel to Blood Money. Dailly was able to quickly produce an animated graphic showing his creations moving endlessly, with additional graphical improvements made by Gary Timmons and other members of the DMA Design team to help remove the stiffness in the animation. One member, Russell Kay, observed that "There's a game in that!", and later coined the term "lemmings" for these creations, according to Dailly. Allowing the creatures to move across the landscape was based on a Salamander weapon concept for Blood Money and demonstrated with the animations.
Levels were designed based on a Deluxe Paint interface, which allowed several of the members to design levels, resulting in "hundreds of levels". There were several internal iterations of the levels, each designer challenging the others. Dailly pointed out that David Jones "used to try and beat us, and after proudly stabbing a finger at the screen and saying 'There! Beat that!', we'd calmly point out a totally new way of getting around all his traps, and doing it in a much simpler method. 'Oh...', he'd mutter, and scramble off to try and fix it." They also sent internally tested levels to Psygnosis, getting back the results of their testing via fax. While most were solved quickly, Dailly commented that "Every now and again though, the fax would be covered in scribbles with the time and comments crossed out again and again; this is what we were striving for while we were designing the levels, and it gave us all a warm fuzzy feeling inside."
