The thing that attracts me to Gamma World and Mutant Future is the almost unlimited potential for creature design. The mutations in both games run the gamut from realistic to supernatural and this allows a GM to design a game that can go into almost any direction. But the mutation system also poses some challenges. It allows new species to appear every day in MF and possibly every few hours in GW. Considering the patchwork that will result from that*, designing a functional ecosystem can be difficult, so here are a few ideas and suggestions. They are not meant to be all used in the same setting.

Do not use radiation. Rather use several different mutagens, each that affects only a certain group of organisms such as mammals, plants and arthropods. If the mutagen that affects plants is not found in a region, the PCs can be less concerned about monstrous vegetation. That does not mean there will be no killer plants as they can arrive in the form of seeds or cuttings, but that there will be less chance of them. The rules for radiation and mutation can still apply, they just don't use radiation any more.

Nanites are your friend. Tiny machines that are free dwelling in the environment can kill off extreme mutants, sterilize them, put them into stasis (to be awoken by the PCs) or modifier their behavior and keep them restricted to specific locations. They can also create creatures whole cloth.

Parthenogenesis can be the key. If mutants are constantly forming and becoming new species that can not interbreed, most lines will die out fairly quickly. One way around this is to remove sex from the equation. Females that produce clones of themselves don't have to worry about fertility, or at least finding a mate. In places where there is high levels of mutation, females may outnumber males 1000 to 1 or more.

Immunity is not that useful. Even though it may seem like a good idea to give lots of creatures immunity to radiation. Yes it keeps the species from vanishing because the chances of sterilization from interspecies mating goes down, but it also attacks one of the key features of the games. It is called Mutant Future for a reason.

Radiation can be food. For those of you who still want to go with immunity, there is a mutation I created, Light to Mass, that was meant to be something like the spell Create Food and Water. Of course it has a lot more applications with and without tweeking. Radiation to Mass helps keep creatures alive in the harshest conditions one will find in GW/MF- the radioactive desert. Groups of plants with this mutation might even be islands and act as the base of a small foodweb (see a couple weeks ago in my blog).

Symbiosis may be the root cause. Instead of mutating most creatures, mutate their internal flora. The changes in chemistry will cause mutations to their hosts. Some may be heritable but most will not. This means each generation may be significantly different from its parents. Or, to flip this on its head, symbiosis protects from mutation. The process that created pure strain humans in GW may have involved cellular guardians that keep mutation at bay.

Generalists will win. Any species that becomes a specialist in terms of diet will die out in GW/MF as their food will change. Only those creatures that have a very broad selection of food (like pigs, carp and humans) will be able to survive for many generations. Or there could be species that are extremely plastic in their phenotype. Many creatures that appear to be different species are actually the same. The environment's effects on the creatures' development in the womb, egg or seed causes the physical changes. And then there are beastal twins (and endosperm mutants for plants)- creatures that produce a type of offspring that exists only to protect its siblings. The stronger the twin, the more likely the species will survive over the long term.

Clone machines may be the source. Factories that created pets and other lifeforms may be the only way that some species survive at all. They simply can not breed fast enough in the wild before predators or herbivores devour them.

Invasions may be common. Ecological sources are those places where a species can breed fast enough to survive. Sinks are the opposite. If a location has enough mutation to kill off most of its species, then add a source nearby. It can be the clone machines in a city of the Elder People, an offshore island, a valley, an nanite infection of a lake (using spontaneous generation) or even orbit. Teleportation technology is not in MF and has just the transmat in GW. So why not add it, if nothing else to add a source for new critters and mutations?

Planeshift screws everything up. This mutation, which was only in the first edition of GW, can really add to or screw up a setting. It can allow for Jedi, dinosaurs, gnomes, terminator 800's, hobbits, klingons and anything else you can think of to spill into a setting and have some impact. In terms of ecosystem design, it can add a lot of really alien critters (Creatures of the Wastelands and Wisdom from the Wastes #7 have some examples I have written).

I should also note that robots are effectively alive for ecosystem design. Being shredded by a lumber bot is no different than a swarm of bark beetles- they both kill the tree.

Life is only one half of the components of an ecosystem. Next I will look at environmental hazards.

* Take a look at the article Life in a Cubic Foot in the February 2010 issue of National Geographic and scale that up to human level (or the book that resulted there of). And maybe increase the diversity 10 fold. That is what a full bore GW/MF ecosystem should look like. Every possible break- a stream, a ridge, a road- can be the signs of an entirely different guild of species on the other side. Mind boggling, huh?