My pleasure.
Yep, I guessed that was the reason. But as your users seem to love your app, and from what I can tell from the description, it is absolutely
packed with info and tests, it seems to me that you should perhaps instead consider selling it for a fixed price. This seems so good that I imagine it's well worth somewhere between $19 and $49. I would problably be tempted to set the price to $39 and during the periods in the year when people start looking for this kind of app have a sale for three weeks at $19. (If you do this, your track-record with the app, the high ratings, will make this seem like a reasonable price I think.) Selling like this does also align with the fact that your users use the app for a time, and then they (sort of) get replaced by new users.
As for the game - sorry, no experience coding games since childhood. I do know there are lots of highly skilled people here in the forum that you probably could get very good help from. Go look in the Games sub-forum to see the people hanging out there.