Timed mode will eventually come, I had some early prototyping with difficulty setting and sometimes it's indeed more fun to just crack as many simple ones as you can
Buuuuuut I also have to share one bad thing. I messed up the game and the progress was not saved. I hope you did not have too many levels there. If you did have I'll provide some workaround to restore it although not possible to do it "automatically". Sorry for the inconvenience