Add a new rule, “Mutation”:-

Each Infected has numerical scores for Mutation, Size, Brain and Limbs, tracked in the GNDT and defaulting to zero, 4, 4 and 4 respectively. Size, Brain and Limbs are known as Phenotypes.

At any time, an Infected whose Mutation is less than 10 may increase their Mutation by 1 in order to Mature. When an Infected Matures, they must decrease one of their Phenotypes by 1 and then increase one of their Phenotypes (which may be the same one) by 2.

If one Infected has a lower Mutation than every other Infected, he or she is known as the Survivor.

Set the Alien’s GNDT values to a Mutation of 10, Size 10, Brain 6 and Limbs 6.