Not a fun platformer. Not for me.
Playing a game which is punishing to the player for the sake of being punishing to the player might seem appealing to some of the hardcore, nostalgic crowd who remember how difficult games used to be, but for me, it's as bad as holding a player's hand completely.
There is nothing fun about being punished for having less than adequate perception of what it means when an abstract flash of light bounces off of a barely visible wall or frame in the shadows. The tools you have at your disposal in order to survive the game, presumably the very tools which ought to make the game fun, are hindered by the sheer unrealistic expectations the game places upon you to anticipate traps. You wind up taking each step one at a time, walking on egg shells with no motivation to complete the game other than completion itself.
A big part of the fun of platformers is being able to move freely and complete tasks without having to stop. Granted, some platformers are more challenging than others and ask the player to assess a given situation before proceeding (take Castlevania series for example), but not to the extent that every single step warrants a second, third, or fourth look as it does in Thoreau.
Spend a little less time mimicking Limbo and a little more time polishing actual gameplay and you might have an entertaining sidescroller.