OtherSide Entertainment developer Sam Luangkhot has posted another update to the Underworld Ascendant website, which gives us a few details about the functional ecosystem that the setting of the game, the Stygian Abyss, will feature:

We knew that Underworld Ascendant needed to be designed as an interactive world, but also one that lived and breathed when the player wasn’t around. Everything from the lighting to the creatures’ animations are all being considered as integral to Ascendant’s world-building.

One element where this immersive ecology has been coming online is mana, which our lead designer Tim Stellmach describes as, “Not only is it the resource used to cast spells, it is actually concentrated in packets in the material world. Characters recover mana by touching and consuming these invisible free-floating bits of mana in the air.”

How does that affect the world? The entire in-game ecology is based around it. Wisps – benign, ethereal creatures who float throughout The Stygian Abyss – feeding on mana in the environment and excrete “sunlight” (infrared, ultraviolet, and visible light).

They fill the role of “the sun” for the flora and fauna in The Stygian Abyss, they are an essential part of the underground ecosystem.Meanwhile, undead creatures, rather than being seen as capital “E” evil, have a parasitic relationship with mana, devouring it to ambulate in a sad parody of life and giving nothing in return.Another recent aspect of this in-game? This “sunlight” leads to flora, which is eaten by various fauna, like our “ambient” creatures, who generally mind their own business in the world, but have interesting behaviors that the player can exploit to their advantage.Our current favorite ambient creature is the Deep Slug, who can be baited with certain types of food and leaves useful effects in its wake, like a flammable slime trail. Toss its favorite food into the patrol path of a few enemies or by a wooden support of an archer tower, add fire, and enjoy. (Feed it something else interesting? And discover the results…)

There’s quite a bit more to this update, so I’ll suggest — as usual — that you click on through to read the whole thing.

But I have to say: coming off the heels of an engaging discussion about Ultima Online and its scrapped Artificial Life engine, it’s edifying and exciting to see that Underworld Ascendant will feature a world that persists and changes when the player isn’t looking at it, or actively exploring it.