Took me a while to realize that you type 'dot' and 'special' to get your basic units.
I was cruising through typing the way I normally do, when I figured, in the spirit of the game, I ought to try to type correctly (using all my fingers and not looking at the keyboard). For me, it's plenty challenging this way. But I did notice a bug. Every time you complete a level the game opens a new one even if you've already completed it. So, for instance I just beat level 3 but, because I had already played through 9 it opened up 10. Also, if I lose on 3 and select 'retry' it takes me to the most advanced level (level 10 now) available instead of playing 3 over again.
The last couple were just getting interesting. Could include a more challenging set. Could add a level editor so that you wouldn't have to come up with the puzzles. Just let users make them for a while and then make a best of user pack.
 "Ink Battle"){kind=icon}
 "Liquid Measure 2"){kind=icon}
 "Picma Squared"){kind=icon}