So I have completed the demo!
But first, screenshots!

Title Screen
Main Gate
Warlock Lord
Subscreen
Item Screen

You can download the demo here.

EDIT: I completely forgot to post the controls.

Arrow Keys are used to move.
Z is choose. X is cancel.
X also brings up the subscreen.
…I think C also does that, but I forget. Just ignore this line.
Oh, and you can hold Shift to dash. I had forgotten that. Sorry.
And, no, you don’t need any other programs to play this game.