It's not an april fool's joke - you can add it to your cart at PGS.
The description there is pretty god damned awesome.
There are three modes and about a hundred different sounds in Keeley’s Würst. The three main modes are Random, Pitch Up and Pitch Down. “Random” is sort of like an LFO-driven random, super-resonant sample-and-hold filter. Pitch Up and Pitch Down do exactly what they sound like, but in the most pleasingly disharmonic way.
The Blend and Gain knobs are pretty self-explanatory, then there is the Proximity (read: how far from the root note the “harmony” is) and Range/Rate. In Pitch Up and Down modes, this controls the range of pitch and in Random mode, this controls the rate of the filter. Proximity and Range in conjunction can get really weird, really quickly. And it gets weird, all right. Weird, even for the Würst.
It seems the last few product releases Keeley has been moving away from the transparent compressor crowd and doing some cool stuff.
Psi fuzz, that fuzz wah (minus the horrible graphics), mu-tron thinger. All looks cool.