Epic promised fully open development on the new Unreal Tournament, and it's delivering. The pre-pre-pre-alpha (or whatever stage you'd call this) was originally available only to people who subscribe to Unreal Engine 4. However, Unreal Tournament forum user raxxy is compiling Epic's builds and releasing them to the public. And Epic's okay with it, even taking in feedback from these wholly unofficial play sessions.
Now, as I said, this is pre-pre-pre-pre-pre-pre-alpha. Pre. Alpha. That means you're missing things that you might normally think are normal for shooters. Like, you know, environment textures. Or a balance pass on the guns to make things a fair fight.
If you're not dissuaded, you can download the latest build here. And it seems fitting that this '90s arena shooter get paired with more old tech—in order to keep up with the latest build updates, et cetera, you'll probably need to check out this IRC chatroom.
And you can get a glimpse of the game as it stands right now from this video:
Thanks to raxxy and Rock Paper Shotgun for making this a fragging great Wednesday morning.