Developer Playdead’s 2010 classic Limbo and its 2016 follow-up Inside are two brilliantly dark titles that should grace the Steam library of every PC gamer. For brave fans with deep pockets, a special collector's edition is being released that costs $375 and has been put together in conjunction with iam8bit and sex doll maker RealDoll.

The Inside Collector’s Edition comes with a disk copy of the game for the PlayStation 4, along with Steam codes for both Inside and Limbo. But it’s the so-called “other stuff” that's grabbing people's attention.

Iam8bit’s pre-order page doesn't reveal what else is in the mysterious box, but it does explain that it comes from a collaboration with RealDoll, which, according to its website, makes the world’s finest love dolls. These life-like models feature stainless steel joints, PVC skeletons, and soft, silicone skin. With prices starting at $3999, they aren’t cheap.

Iam8bit, which released a working SNES cartridge of Street Fighter 2 last year that came with a fire warning, says the Inside Collector’s Edition will ship “when it’s done,” and it’s only at this point will the contents be revealed. There are a limited number of units available, and as this is a timed release, pre-orders will permanently cease after June 8.

Spending almost $400 on something when you don’t even know what it is sound risky. But whatever it turns out to be, the item is definitely heavy. The page notes that “this edition weighs a surprising amount, hence associated shipping fees and tariffs.”

For those who haven’t played the game, mild spoiler alert ahead.

There could be one clue to the contents: the wrapping on the present box contains images of the creature that appears at the end of Inside, so perhaps RealDoll has made a smaller, realistic replica of it. The object might even be one of the game's lifeless grey bodies that are manipulated with the mind-control helmet. If it turns out to be either of these, one would assume they can’t be used in the same way as RealDoll’s other products.

Pre-orders for the Inside Collector’s Edition begin this Thursday, March 8, at 7 a.m. PST. Shipping is available worldwide, and the item is expected to arrive in the first quarter of 2019.