The newest addition to 2400 is Nuclear Family — a game about braving the wasteland with your misfit buddies in a gonzo, post-apocalyptic future. (And my attempt to answer folks who wonder whether a super-short game can be used for long-term play!) This builds upon my work in Wastoid (a post-apocalyptic hack of Knave, still a work in progress), but in a super-slim format.

You can read the full devlog at the Pretendo Games blog. Here, at least, I'll highlight how you might use this in combination with other 2400 games:

Use it as a template for your own long-term campaign. For those who feel the main things an RPG needs to be "suitable for campaign play" are lots of upgrade options and gradually-paced advancement rules, this game means to present a way to do that in just a few pages. It may take some editing to adapt it to other settings, but in case it would be helpful to have more broadly familiar skillset names, try Strength, Dexterity Intelligence, and Charisma. 

Mine it for mutations & talents. There's some overlap in Nuclear Family with other Eos and Legends, but most of what's in this big list is new to 2400. You may need to rename some talents to fit into the tone of other games, but there should be plenty of upgrade options here for characters in 24XX games who can take talents when they advance. 

The mutations, meanwhile, might be ported directly into Zone, Xot, Exiles, Xenolith, Junior Hybrid Battle Cryptids, or other 2400 (and 24XX) games. That said, these are meant mostly as samples or suggestions; mutations should be a little easier to invent on the fly than talents (which demand a bit more thought about how they'd interact with the rules). Basically, think of something cool that an animal, vegetable, or mineral can do that humans can't do, and hey, you've got a mutation. 2400 doesn't have many "stats" to interact with, so the key thing is just coming up with something that expands what characters can do.

Use the healing rules for a more D&Dish or video-game feel. Most 2400 games hand-wave healing a bit — pay for medical treatment, or wait to get better. This one is more inspired by video games with "medkits" or "stims," or D&D with its healing spells and potions: Use "medicine" or sleep awhile to clear away relatively minor hindrances (like dizziness or a twisted ankles), or see a doctor for the more serious stuff (like broken bones or radiation sickness). If you appreciate the simplicity of healing goods, but still don't care to bother counting hit points, this might suit you.

Use the item breakage rules for resource-scarce settings. Nuclear Family suggests that you can break a weapon for a d6 help die on a roll, in addition to the usual armor breakage rules. If you want to go even harder, you can add back in a rule I decided to cut, or one like it: When you use a weapon or tool that's in poor condition (which is most of them), it breaks on a 1–2 roll IN ADDITION TO any other risks you faced.

I cut that more punitive rule because it felt like an annoying thing to have to remember to do, as opposed to choosing to break an item for a potential benefit. But if you really want to drive home just how hard it is to get good gear, that's one way to do it!

Visit this planet in another 2400 game. If you want to situate Nuclear Family in a larger 2400 setting, this doesn't have to be Earth. It could well be some other world — an extrasolar colony founded by jingoistic American "pioneers," once riding high on the cloying boosterism of their successes, giving way to barely suppressed anxiety over the real (and eventual) threat of nuclear and biological warfare. It might be… 

• A failed colony residents are too poor, too proud, or too wanted-by-the-law to leave, receiving occasional supply drops from Cosmic Highway crews
• A "lost" colony, rediscovered by an Eos crew years after everyone thought it had been utterly destroyed
• A quarantine world under orbital blockade (like the one in Exiles), but still a tempting destination for rogue scientists and salvagers

Then again, it might just be post-apocalyptic Earth, as Wastoid is meant to be. I leave it up to you. And when I do finally finish Wastoid, I hope you'll find some stuff in there you'd be happy to use in Nuclear Family, or vice versa. After all, I'm of the mind that there's no such thing as "too many" post-apocalyptic RPGs.