I say I am using Mutant Future rather than running or playing it, because like many older school RPGs experiences and interpretations of the rules of the game will vary widely from group to group. Equally interpretations of the game setting can vary a lot. I'm not really that into the Fallout, Mad Max, dudes with sharp bits of metal and tentacles protruding from their bodies type of post destruction world. I either like the very grungy A Roadside Picnic, Stalker, or Metro 2033 type world with grimy guys climbing around in rain coats and cheap anti radiation suits with sawn off shotties, or a more low fantasy approach like Nausicaa Valley of the Wind (A great Manga/Anime). For this game I decided to set it in a more Nausicaa type world. A world long after 'the fall' with a medieval come age of gun powder tech levels and a very fragmented tribalistic society. Whilst it isn't a fantasy setting, it can feel like one, with myths, legends, cultures and monsters that create a world unlike our own.
A cover from Miyazaki's Nausicaa Manga.
Once I'd started down this comics track, I decided to throw Arzach in, and have some of the mutant factions riding around on dinosaurs and even use Arzach as a character.
Arzach, by Moebius, Heavy Metal Magazine
But what about the book, and the game system itself? Mutant Future is Goblinoid games attempt to create a modern clone of Gamma World. I've never played Gamma World, it predates me so I cannot give a comparison. What I do know, is that the system is really just a tweaked version of Goblinoids Labyrinth Lord, which itself is a clone of D&D basic. This is the first time I've run a game using the D&D basic rules, other than Dungeoncrawl Classics which uses a lot of the modern 3.5 D20 rules engine. Mutant Future is purer old school, and I have mixed views on this. Older rule sets, D&D or traveller, were vague and incomplete, and this is what made them great. You could fill the gaps yourself, no rules lawyering, easy loose systems. In Mutant Future I've found myself plugging a lot of the gaps with rules from DCC despite it being a D20 system. There are two things that bug me about Mutant Future, and at one of them applies to D&D basic too. The first thing is the lack of one unified dice check system. Combat is done with a D20, hiring retainers 2D6, or trap detection uses 1D6, determining the function of ancient technology is a D100 roll, a moral check uses 2D6, an ability deck is a D20 but roll low etc. Each system or check uses a different die. This creates two problems for me, firstly I'm constantly look up rules, or just forgetting them and winging it, secondly when we come across a situation which is beyond the rules, such as blagging a guard, I am unsure which dice to use and what numbers or stats to use as the basis for the test. I can improv this, and do, but other games such as DCC make it easier to make the improvised decisions. Here I can get inconsistent, asking for one roll on one occasion, then a different one for the same challenge on another, because I simply forgot what dice we used last time. The second issue is health points. Mostly players start with 50ish. This may not increase that much in the game, setting the game apart from D&D where hit points start low and rise over time. Combined with many monsters having high hit points and the melee weapons at the start of the game being fairly low powered, D4-10 damage typically, combat situations can often turn into slogs. I like short deadly combat, where monsters or PCs can die at any moment and the fight only lasts 4 or 5 rounds and about 5-15 minutes of real time. With so many hit points the party had a fight with five sentient spear wielding bird men lasted nearly 30 minutes and only ended when the birds started to fail moral checks. Only about 20% off attacks connected, and then chipping away from pools of 30hp or more. Things take time. The game takes this route because the high tech weapons, plasma rifles for instance, do silly amounts of damage (8d6!). At the high tech level the high health makes sense, but at lower tech, a normal low level human should withstand at least one clip from a submachine gun. It creates a level of grindyness to the fights and forces me to adapt the rules heavily for taking out incapacitated or surprised individuals that could logically be one shotted. These shortcomings don't kill the game by any means, I still like it as a whole and will run this game through, and many others over time, but I would jump ship to a DCC post apocalyptic game in a second.
What I've learned is, that I am not a true 'old school' roleplayer I guess. There are many trappings of modern rulesets that I prefer to the old days. I do look forward to some AD&D and basic D&D, but only because of the ethos of the game, the superior art, and the wealth of good quality modules out there. I doubt I will invest in another pure retroclone for the love of the system itself.
For more info on the game; http://www.goblinoidgames.com/mutantfuture.html. Print editions can be picked up at Lulu.