Hi, I'm new to the forum. I just register.
Maybe what you are looking for is something like this:
http://www.jalmus.net/?lang=en
Random notes on a Clef and you have to play it in time on your midi keyboard.
And a great program like Guitar Hero but with a piano and where you can use de midi files that you want is Synthesia:
http://synthesiagame.com/
You could use the free version with the notes falling into the keyboard, but if you buy it you can unlock the Grand Staff and use it for sightreading. You can choose learning mode where the song stop until you play the correct note on your keyboard o play mode where you try to hit the notes just in time.
Synthesia is very funny, I have the features unlock and use it for sight-reading, there is no better software for that. I'm a beginner, I buy a digital piano a month ago (I play guitar and bass, but never play keyboards before) and the first song I learned was the intro to Space Dye Vest using this program.
I Hope any of this help you.