I really loved the atmosphere you built here; it does an excellent job of giving a real sense of exploration. Combined very well with the awe-inspiring background ambiance audio. For something whole core was made in about a day and a half; this is an incredibly solid platformer. The sense of scale is especially impressive, from carefully lining up the 1 unit jumps in the beginning to suddenly flying across multiple screens when you gain height or fall from far above. I played this all the way through and was completely hooked. The power-ups are used really well in the level design, and the Vania elements felt meaningful, especially having to revisit areas with a more careful eye. Also, good job on making me completely forget that pretty much the only sprites were different types of cubes. Super impressive work.