Digressing from the gamey bits for a bit…
I think in terms of art style, it needs to be tight and really concise. The collage-y thing could be cool if done right. But I feel given the time…
What about a black and white style?
Limbo
One Upon Light
Okay, some that are not entirely black and white…
Everyday the Same Dream
Inside
Badlands
Toby : the Secret Mine
Hue
Soulless
Feist
Albert and Otto
Closure
Selma and the Wisp
Tulpa
Bulb Boy
Typoman
Type:Rider
Night Sky
Soulless Night
Doors
Rememoried
Deer Man
Back DeviantArt was still a thing, there was a creator named Katy Towell that made animations of creepy children.
Link: http://skary.com/
Hmm… Or is it too overdone?