Not sure if demanding or just badly optimized, but Miasmata and The Vanishing of Ethan Carter are prone to frequent graphical stuttering and hickups even on my new rig with mid-range graphic card.

Akalabeth: World of Doom. Fried my CPU in a matter of minutes.

I think Carter is more on the demanding side. It's doing a lot of atmospheric fog, distance blur, and huuuge textures. I'm sure it could be bested as optimization is a neverending task, but it seems to legitimately be using the features to achieve something. It's also freakin' gorgeous.

What PC did you compile?

I would like to love it, too, but my fun was marred by those hickups and more importantly the inconvenient save system that seems oddly out of place in an adventure game based on exploration (checkpoints, and half-solved puzzles are completely reset when you quit the game). :( But that's going a bit off-topic, sorry.

Those reactions all seem pretty understandable to me. I had to turn everything to low-ish on a GT640 to get an okay experience. The worst part of the progress tracking is that you can reach a point in the game where you learn that you missed things (near the end) and you're required to hoof it all the way back. It's a pretty place, but that design choice does its best to make you fail to appreciate it.

IMO it's a game to play in a couple years when the requirements aren't high anymore, and isn't terribly worsened with some mild spoiling.