Mutagen is a custom-made campaign setting of post-apocalyptic science fiction, along with a healthy dose of survival horror.

It’s an “on-and-off” campaign that we’ve been playing when our other rpg games reach a standstill or go in a break. It was designed in a single afternoon. Then redesigned and concepts altered two or three times since then. It started as a Gamma World d20 campaign. Then evolved into d20 Apocalypse in the Gamma World campaign setting. Then a number of custom-created factions were introduced, creating an even higher layer of “worldwide influence” than the one portrayed by Gamma World. All the while, my players had only managed to leave their village, find a town where they lived in and without a lot of explanations, forced to relocate once more in a vast Arcology where things made little sense.

That’s where we paused our campaign the last time.


Zombie flicks, fallout games and most specifically, watching “I am Legend” and finishing the “Gears of War” game all during the same week. In my second re-design of the campaign, I was heavily influenced by power-armor rpg concepts and even Mecha designs.


(The fluff will be in the wiki!)
It’s a d20 modern game in which I’ve tossed rules and equipment from almost every d20 product I own. The major core is d20 Apocalypse, with its salvaging and post civilization survival system. Equipment trickles down from various PL’s and there is a large distinction when the time came to incorporate material from the Spycraft products.

Spycraft weapons are better. They have more range, more damage (some times) and generally a much broader range of selection and traits than the d20 Modern ones. Therefore, the Spycraft material is available only to some special, or elite people. The rest of the world can fight their fights with the simple guns of d20 Modern, with rifles that have 110 feet range increments. When an elite team takes the field, armed with a simple Spycraft rifle that deals more damage (3d6+2 as opposed to 2d8) and has more range (225 feet as opposed to 110 feet), the difference is evident. So, the people armed with these stuff, are a force to be reckoned with.

To satisfy our various needs on proper portrayal of the crumble of civilization and differences in capabilities from settlement to settlement and faction to faction, several house rules were incorporated. Now, it’s time to copy these over from my google docs folder, in order to have everything sorted neatly and nicely, and how knows? Maybe even inspire someone to run a game in this little version of a post-apocalyptic world.


apophis Mutagen banner