Grobots is a programming game in which robots capable of reproducing compete to survive each other's presence. They are limited by energy, which can be obtained (and spent) in a variety of ways, and by their hardware, which restricts what each robot can do. Robots can move, sense, think, eat, reproduce, communicate, fight, and die - all without human intervention.
Sometimes Grobots seems more biological than mechanical. This is deliberate. You can think of robots as cells if you want; we often do. Note, however, that there is no genetic variation and therefore no evolution; this is not artificial life. A side is more analogous to a multicellular organism than to a population of individuals.
A Grobots file describes a side: one group of robots in the competition. A side may contain multiple types. Each type describes one sort of robot on that side, with its own hardware and software.
For example, a side might contain a gatherer type, which collects food and makes more robots, and a warrior type, which defends the harvesters. Many former champions fit this description.
Each side starts with a small group of robots. They gain energy from sunlight, or by collecting manna, or killing and eating other robots, or even theft.
Each robot is controlled by a program in a simple stack-based language. This follows RoboWar, although the Grobots language is more powerful.
Grobots takes place in a two-dimensional rectangular world. The size can vary, but it's large - usually more than a thousand pixels square. Distance is measured in units of 16 pixels; a one-unit grid is visible on the world.
There are three important kinds of objects in the world: robots, shots, and food. See the fake screenshot (or a real one) for examples of all three. The large colored circles are robots. There are two types of shots shown: blasts (pink things) and grenades (little yellow circles). The squares are food - red for corpses, green for manna.
There are many sides (ten or more) in the world at once. Each one starts with a seed of a few cells. The object is usually to accumulate as much biomass as possible. The round ends after 18000 frames (about ten minutes). It will also end when only one side is left, but this rarely happens.
Grobots by Devon Schudy and Warren Schudy