Forgive my sparse posting as of late, (and curse my sparse reading...there are a lot of good entries I need to brush up on) but I have been called away by various aspects of real life.
My game is set to continue tomorrow. I've been running for nearly five months and I've only missed a single session. I am quite proud of this.
As I mentioned in a previous post, I want to keep the game AD&D-centric, since the world they are in is only Gamma World-esque, and not actually Gamma World. (That is to say, 25th century North America after the "Social Wars")
I recently discovered an article in one of the Dragons I picked up a few months ago that had advice for crossovers between AD&D 2nd edition and Gamma World 4th, which are close enough to what I am running. Sadly, the article seemed to have too much of a "never the twain shall meet" type of attitude for my tastes. If you're going to give your players fusion rifles, you should expect that they will want to use them. The article seemed to preoccupied with letting the players get a taste and then snatching it out of their hands at the earliest opportunity. The article also says no mutations on fantasy characters, and no magic for Gamma characters. Fantasy characters have no resistance to radiation, and Gamma characters cannot save vs. spells.
Fie on that, says I.
Magic, in my milieu, was brought to the characters' native plane by a dimension traveling race called the Magi. They have died out, and perhaps they never visited Tarraxian... or, perhaps, it could be that Tarraxian is simply another planet on the same plane as the world from whence they came. Magic exists on Tarraxian (and works, though somewhat unstably so), so I speculate that radiation would exist on their home world if they had reached the atomic age.
I have found a good rule of thumb for converting Gamma World monsters is to cut their HD in half and convert the die type to d8. It's not perfect, and it certainly works for some monsters better than others, but it will do in a pinch. I have also started adding my own monsters, so far I have run them up against a parasite that drains energy from energy cells, and grows larger when hit with lasers or similar energy weapons. My brain is churning out ideas for more as well.
I'm really glad the campaign took this direction. More later as I continue to develop and convert things I'm satisfied with.