RobertSaturn, I did some digging as well to see what I could use to practice for the stage 2 tests. I found out about that app (and a few more like it), but I don't think I'll be buying anything. From what I've read in forums, FEAST is designed to test your skills, rather than your preparation. I'd guess it's a bit like the online assessments, preparation doesn't matter nearly as much as being able to think quickly and clearly. That's why I don't think the investment is worth it.
However, I've been checking out some nice tools to get acquainted with the brain exercises/ATC stuff. There's a few that I've found to be interesting:
Airport Madness - multitasking, awareness
Lumosity - full of little games to test speed, attention, memory, etc. Some contents used to be free, I believe, now after an initial test you have to pay a subscription fee (about 7€ a month)
And, of course, the NATS games
Btw, what do you think would be a nice score on those NATS games? I struggle with some more than others. In particular, what do you think would be a good score for the sequential memory and reactive avoidance tests?