It took me a bit to realize that you had to make the shape shown to you in red since it wasn’t like recess in the board or anything, I kept trying to mirror the form after I figured out things could be joined together.
Also I kept making shapes that were isomorphic(the same shape as the solution) but had a different diagonal. It was very annoying and I didn’t find an undo button.
Still an interesting little time attack game. made me feel like I was actually on the clock and being cognitively tested.