Every hopeful gaming thread on the Internet has at least one person making this kind of guess: Valve Software will one day drop its next major project as a previously unannounced, out-of-nowhere surprise for immediate download. And it’ll do it for free, just for funsies.

Valve did exactly that on Wednesday. The release even kinda-sorta has a “3” in the title, but it’s pretty much the polar opposite of what you might expect: a massive, multi-functional middleware solution for more realistic and efficiently rendered 3D audio.