The tenth 2400 release is Tempus Diducit, an extremely transparent excuse to mash all the 24XX Jam games together, and to make a bunch of really weird backgrounds in a singularly stressful week. I'm making it free as a "demo" on the 2400 page for at least the duration of the jam, which runs through November. 

Tempus Diducit is extremely vague about its setting. Is it a post-apocalyptic mishmash like Palladium's Rifts RPG? Is it a time travel game, and if so, can anybody do it—or can anybody even avoid it? These are good questions, and I envy you in figuring out the answers. When I run it, at least, it will be somewhere in between those options, and I'll probably make an occasional luck roll to see whether you end up in the same world you started in. Good times (so to speak).

Thanks also to those of you who've pointed out to me that 2400 has grown to a large enough number of games that it's kind of a pain to stick them all in one folder. Now you can choose to download just the single-page versions, just the spread versions, or just the black and white versions. I hope this helps, but let me know if you have any ideas for what might work better!