You’ve got to have four core classes, don’t you? (No… it’s better than that. You have to have originally had three core classes… and then later add the fourth in an expansion. That’s just how you do it.) Here’s a broad overview of each one:
Pure Strain Humans: For the folks entering into the franchise with this edition, this character type is the least understandable. Sure, you get some significant bonuses to stats and hit points, but really… your big claim to fame as a PSH is that you don’t have have any mutations. (You know… those cool powers that are kind of the entire point of the game…?!) Worse than that… these guys can only understand 20th century level technology. Judging from the pictures, these guys were practically pulled straight out of the eighties somehow. Now, I understand that the Tech V artifacts are meant to be a mystery… but all the iconic pictures of people using road signs for shields and wearing sports equipment for armor… it effectively makes the campy sci-fi Tech IV stuff a mystery as well. “I’m a pure strain human, a descendant of man and resistant to mutation… but who am I really?” I have no freaking idea!
Humanoids: These guys are the stars of the game– at least to my default teenager imagination. They get 1d4 Physical Mutations and 1d4 Mental Mutations. Yeah, if you roll a one for each of those… the whole table will laugh at you. I suppose a wussy Gamma Master might be convinced to let you pick your stuff in that unhappy event, but honestly… half the fun in this game is from taking whatever weirdness the dice give you and then making it work anyway. You just need to understand that absolutely no effort has been made to “balance” the capabilities of the player characters– both between character types and within character types.
Mutated Animals: This is just like the humanoids except this character type can’t use tools as well. If your mutant animal doesn’t have hands, you can’t use tools at all. I love this bit: “Natural abilities and limits of the original stock must be decided by the GM.” Oh, yeah! You know, in the seventies I guess you could get away with this sort of “why have us do any more of your imagining for you” thing. In the eighties, it just looks like you didn’t bother to… you know… actually design a game or something.
Mutated Plants: The new guy! This is a good choice for the nonconformists of the group. Yeah, you get fewer mutations– 1d3 each for Physical and Mental– but you don’t need food, you can regrow crippled limbs, and you can sort of resurrect yourself from your roots. Those are all really groovy abilities… but frankly, we did not bother to track food back in the day, we ignored the various special damage types of the combat system that could conceivably destroy limbs in favor of a kid-style wear-down-their-hit-points approach, and I don’t recall a single player character death from out of any of the sessions we played. (I’m telling you, humanoid is the way to go here. There really isn’t any other option!)
Symbiots: Okay, there is one variant of the mutated plant type that gets a lot of verbiage here– it’s practically its own class. These guys get an extra mental mutation… but they are not really all that planty. This is really more of a mind-control fungus or something… which should be awesome, right? Ah, but symbiots are slow and maybe even unable to move. You’ve got to have a host creature. Which is fine… but the rules assume you’re only going to take over “nonintelligent” creatures. Okay, maybe I could work with that… but why? And then there’s this: “The GM should allow the symbiotic plant to inhabit only common animals when it first begins the game. A symbiot may not change hosts until the original host dies.” Which is all to say… that this is potentially the most awesome ability in the history of gaming, but the game designer has to nerf it any way he could no matter how little sense it makes. And he has to do that when he didn’t lift one single game designing finger to bring any sort of “balance” to the other classes. This is just nuts already. If you can’t handle real wahoo! adventures with completely unexplainable and unbalanced player characters roaming around in a world that makes absolutely no sense… then you’re playing the wrong freaking game. The reticence on the part of the designer with this half-thought out mess of a character type simply does not fit with the tone of the rest of the rule set. Seriously, you need to be able to go in full bore with a game breaking symbiot class, or you need to drop this thing from the game. But that doesn’t matter in actual play, because everyone knows already to take mutant humanoids. So this travesty of game design doesn’t really impact the game at all even though it should.