I love the ASCII aesthetic but I feel by snapping the player to a grid, the platforming suffers. I believe you could have kept the graphics but use all those extra pixels to allow tighter platforming controls but that's your design choice (plus idk how you coded it making that impossible to change). I also think that the checkpoints were too far apart. For example, the first checkpoint in the sewers is far from the "I hope these grids are solid enough" part where I died a lot. I would end up rushing to get back and end up dying again along the way. It felt annoying and a bit of a time waster which was when I quit.
Overall this is a super cute game that I would like to play through when it's finished!