As it stands, for now, the 24XX ruleset and all its related games are primarely focused on one shots and short campaigns. Has any attempts been made for a 24XX game or rulehack meant for longer campaigns?
I wrote a bit on my blog about how I intended 2400: Nuclear Family to provide an advancement model for longer-term play. If the main rubric for what supports “longer campaigns” is indeed pace of advancement, and you want to stretch out even longer, I recommend considering more granular skills (like those used in Inner System Blues, rather than the broader skillsets of Nuclear Family), and potentially increasing advancement requirements, as suggested in that post.
By the same token, some groups play quite long campaigns without regard for mechanical advancement incentives with these rules, but they tend to pull in content from elsewhere or have GMs who’re good at improvising. The rules are fine if you are a fan of simple rules, but the games are short! When I ran Xot, for instance, parts of my campaign were built on content from Ultraviolet Grasslands and Numenera, and I’ve run space campaigns cobbled together from Mothership content.
Hope this helps!
Glad to hear that helped! Also included within 2400, check:
There are also cyberpunk games in the 24XX collection.
I personally enjoy running other games’ modules with 2400 and just ignoring their rules, as well, like Aeon Wave and A Pound of Flesh.