4 stars for the whole series; that one star was mostly lost in Deepest Sleep.
Each level of this game series provides an entertaining combination of horror and puzzles. Deep Sleep is the crude introduction that immerses the player in the game's theme. Deeper Sleep is a more refined dark ambiance with the storyline explained in depth to link the player to the shadow figures, and Deepest Sleep provides the closure. Why Deep and Deeper are great is pretty self-explanatory, one finds after a quick game. Forcing the player to move their mouse slowly in the presence of a bottom feeder was a prime opportunity for jump scares either by sound, visually using shadowy silhouettes (the figure in the classroom in part II is a perfect example) or a combination of both. But though some of those aspects exist they were used to their full potential in the first two games,
Deepest Sleep wasn't a disappointment either, but switching to a different monster type at the end and making it out to be the "scarier" threat didn't quite work, especially that in order to fend it off, all what one had to do is nothing... literally. Moreover, looks wise the bottom feeders are monstrous and have menacing teeth, but they're nowhere near the mystery of the silent shadow creature that stood tall with glowing eyes staring at you, in act they were scarier since the player never knew the anguish they could cause if one of them would catch him, and in a way it was more intimidating than getting devoured by a big worm. Then there is the fact that bottom feeders are not that linked to the storyline, yet the player finds them as the main threat to avoid in the series finale instead of say a single intimidating demon or a king of the shadow creatures.
This part III wasn't bad and again, credit where it's due; no horror game ever made in pixels has the same effect as the deep sleep series. "Deeper" Sleep was the best of the series and perhaps it had a hand in raising the expectations up through the roof, "Deepest Sleep" just didn't meet them all. A lot of elements from the previous parts were left out and could have been used to great effect; like the appearance of the disappeared children except Cody as the player couldn't save them all(part II), Felicity would escape the attic and follow the player, perhaps block his escape path, the other traveler (part II)would reappear consumed by the shadow creatures. Bert's -dead-appearance was good, but if his hanged body would have later gotten mangled or -like his poster at the lighthouse- disappeared, or have him jump out chase the player near the end... storyline be damned, if I saw a deranged clown running towards me in the dark, I'd run fast enough to make Usain Bolt look like a b*tch!
In any case, the game series overall is a good creative effort that I've enjoyed and definitely worth recommending for those home alone and still up at 4:00 AM. And each part has a satisfying ending.