This is a generic engine designed to simulate "Darwinian" evolution.
Our "organism" has 3 genes of 3 manipulatable codons each. The genes begin with the ATG "START" and end with the TAA "STOP" sequence.
The genes we will experiment with represent generic attributes, however for the sake of naming conventions in this example they will specifically represent a formula to generate ideal conditions and resistance to Alpha, Beta, and Gamma radiation respectively.
Instead of using real-world physics/chemical modeling to determine the behavior and benefit of the DNA-codon produced chemical sequence, you (the user) has the ability to assign them arbitrary mathematical functions.
Combined with the ability to choose the environmental pressures, the user is empowered with the ability to make arbitrary natural selection criteria.
Please note that this is an extremely simplistic example, in reality gene functionality is never so clear-cut, and most of the time the code is also compressed in a very strange (but very high-performance biologically) way.