A really nice game and idea!
And like some mentioned, there's a bit of tedium here with changing modes, but that can easily be fixed with some simple changes. Like a quick pop of the ghost then having the shape coming down so the ghost doesn't need to go aaaalllll the way up before you can use the blocks.
Another issue: Having to hold down to bring a block down adds to the tedium. There could be a set of lines to show where it'll land, and then pressing like, UP can send it. Or, Up can change the speed that they fall so you can have special things that destroy the blocks on the way down, and changing the speed can "dodge" them.
X should just change the modes right away. Having to hold it down isn't necessary for a game with 2 options. (Granted. This would change as you change the control scheme, Like WASD and/or controller)
Also ran into a bug where going through a door with a block to the right of the door (Not ON the door), blocks the player from entering.
Great game though, and thanks for playing mine! :D
EDIT: Oh. You can also make puzzle areas, where you're given a specific set and pattern of blocks to use. Can restart the stage as well. This way, the blocks can actually be challenging, as opposed to their light restrictions.