Finished the demo and I loved it.
Addicting, love the diagonal projectile concept because it's unique and you can take the deflection to your advantage.
Also love the use of traps like the floor that can be a hole or the lasers.
It does a good job feeling like something out of MSDos.
My one pet peeve was when you move, you sometimes feel like you're stuck and you have to be a bit more seperate from a block/wall just to move or something.
Not sure if it's to do with the player's collision but still a tiny thing.