Conceptually, I loved this. I dug the idea of something from within slowly destroying a host while said thing slowly gains consciousness. I like how that idea was conveyed visually with the early levels having an empty husk of a body and later on the organs and whatnot inside of the body are slowly defined by the thing. I specifically like that the icons changed because it gave a sort of unspoken denotation to the mechanics. Red is stuff you eat, green is what you discover. I also loved the poetic way in which the thing spoke giving the player what little plot was there.
However, I feel as though mechanically the theme of greed wasn't conveyed very well up until the final part. Having to mash the arrows in order to see which one lives or dies puts the player at the forefront of the struggle the thing has against the host. However, I don't feel enough was done to really convey the struggle to the player. Granted, the thing definitely said that we were struggling to "take back what was stolen", but nothing really felt stolen. Nothing was really done in the game mechanics to convey the sense of loss the thing was talking about.
At times, I feel as though the plot suffered from something I like to call "Art Game Syndrome". Wherein nothing is explained or contextualized to the player because fuck you it's art and if you don't like it, it's probably too deep for you. I get that there may be a want to leave something up to interpretation, but people interpret things if it's open or not. Just look at Holocaust deniers (HEYO!).