Swarm visualises an ant colony optimization algorithm.
Ant colony optimization algorithms on wikipedia:
“In computer science and operations research,
the ant colony optimization algorithm (ACO) is a probabilistic technique for
solving computational problems which can be reduced to finding good paths through graphs.”

The program allows you to adjust various values like the
pheromone emission and decay. Graphs can be generated randomly
which also can be viewed as a nice landscape simulation next to an anthill.

There are downloads for different platforms (Windows, HMTL5 and Android).
Very small resolutions (400×300) are supported,
so old devices with small displays can be used, too.