I downloaded this, and I have to say I'm disappointed, even for a free app. Here's the list of "drills", some of which are just one shot to practice over and over.
1. Position drill
2. Circle drill
3. Follow drill (2-rail)
4. Follow drill (3-rail)
5. No-rail drill
6. Basic rail-shot drill
7. Basic L drill
8. Progressive drill (a, b & c)
9. Safety drill
None of them are particularly good drills in my view - the instructions are bare minimal and only one or two of them are progressive. The "Safety Drill" is laughable. You can get much better drills from the SFBilliards website (or many other places).
However, it says new drills will be added...
pj <- no offense to the OP
chgo