The sprites remind me of cave story which is appreciated. Bouncing off the walls with the sword is a fun mechanic idea. This may be a personal preference thing but the controls/acceleration feel extremely floaty to me. I wasnt able to get the block placement to work, i can bring up the cursor but 1/2 dont do anything and left click only removes blocks. maybe im missing something.
Its a nice prototype! could definitely make some fun levels with this with some additional block types