What hides between Shadow and Light?

[Kedjane]

The "hole digging creatures" refers to the hole digging creatures in the games most likely, the rock worms that is.

Considering that the new game will be most likely in entirely new setting and separate from Penumbra series, I wouldn't expect rock worms there, nor in any puzzle about the game. Also I don't see any problem with referencing bugs, as bugs are natural during development of every appliaction and they are going to stop the infestation.

Hole digging hardly is a common way to reference bugs in any matter. Referencing code bugs when you want to get players anxious for your next game isn't a very good strategy either. It's like saying "Hey, our new game has lots of bugs that we'll try to fix" instead of "Our game will contain mysterious hole digging monsters, buy it!".