Viability: the game is playable from start to end, with mechanics that go well beyond class demos. While the jumping challenges are a bit on the difficult side, I found the gameplay expressive overall. I would have liked to see something a bit less linear, with paths that have one more than one solution. Overall, solid stuff.
Presentation: expressive art and charming music. More variety in enemy design and world building could help create a stronger theme, but I can see the effort and care in crafting the assets. The final NPCs are a nice touch, although I would have liked to see some unique background elements also.
Theme: is a straightforward platformer with a simple story, but I do find it curious that the enemies and the MC are ghosts, and that the world seems distorted. Is a bit of an 8-bit nightmare look, which is definitely worth exploring further. There are only a few examples of lo-fi spooky games, so yours is definitely feels fresh.
Engagement: Hard, but not enough to want make me want to quit. More levels would be good, and as I said, more visual variety and reward. Keep in mind that hhen your player wants more, that's a good thing! Keep it up