Twin Peaks

[Saturnome]

I’m guessing some Alan Wake style third-person mystery.

An old school LucasArts style point and click like Maniac Mansion could be great

The creator of Maniac Mansion, Ron Gilbert, did that about 10 years ago with Thimbleweed Park

[eerik]

If the leak is accurate, there were only two placeholder achievements, one of which was a test. I'm not sure this is anything we'll actually see in the future, but ya never know.

There was also, somehow, a full list of achievements for an Alf game.

Yeah, I would not read too much into this. The "leak" was Steam's API exposing achievement (trophy) data for unreleased and unannounced titles, so crawlers have scraped a lot of achievement data for various packages on Steam's back-end. One such package has two achievements associated with it:
1. Test Achievement (This Is A Test Achievement)
2. Welcome to Twin Peaks (Reach the Double R Diner)

And that's all. There's no title, no developer, no publisher. Might be an old abandoned package, or, more likely, given how open and uncurated Steam is, someone's fan project that is not licensed nor officially associated with Twin Peaks.