The following section contains information from a previous version of StarCraft II which is no longer valid.
Banelings were conceived as a replacement for the infested terran. The problem with infested terrans in the original game was that acquiring unit required a lot of time, energy, a terran opponent, and even then, had to make it into closer quarters with the enemy to justify its cost. While the developers liked the idea of a zerg suicide explosive unit, they wanted one that would deal more area damage and be easier to produce in the early game.
As of April 2008, banelings have been increased in size from previous builds to make it easier to focus fire on them. In addition their splash radius was increased. The supply cost was higher.
Banelings were designed to punish opponents foolish or careless enough to leave their forces clustered in large bunches—prime targets to receive the most damage from a bunch of exploding bugs. The developers expected players to struggle with spacing out their units against banelings. Terran players got better and spreading out their forces to minimize baneling damage. In response, zerg players got better at maximizing their creep spread, using it as a speed boost for their banelings.
One dilemma with the baneling throughout the development process was the display of team color. Since the explosive ability of the baneling yields green corrosive acid the predominant body color was green and completely overshadowing the small areas that were team colored. Identifying multiple zerg player ownership of banelings was problematic. Later an attempt was made to have the glowing bubbles on the baneling completely team color and even adjusting the explosion color to match various team colors used by players. This quickly made multiplayer look like a ridiculous Jackson Pollock painting whenever multi-colored banelings were seen exploding at the same time. After other various adjustments, such as just the front two bubbles being team colored, the decision was made to fade the team color along the body, with the forward bubbles being pure team color and the large rear bubble remaining green.
Heart of the SwarmEdit
The following section contains information from a previous version of StarCraft II: Heart of the Swarm which is no longer valid.