From the designer:
A simple set of quick playing rules to develop quick and dynamic play. Published as pdf files and available through online printing services. Includes support for play in a variety of eras, including Superheroes, Fantasy, and Science Fiction.
The Basic Action System games are played with two ordinary six-sided dice. Each character is represented by three stats rated from 1-5- Brawn, Agility, and Mind.
When you attempt to do something, you roll the dice (2d6), and multiply the relevant stat/power/skill by the dice roll. If you roll doubles, the dice explode, meaning you get to roll another die and add the result before multiplying.
Each game has its own list of powers taylored to the genre. Powers have defined effects, but the description of how they work is left for the players. Powers are meant to be customizable. The "Special Attack" power, for example, could be used to make indestructible claws, energy blasts, fireballs, a magic sword, etc.