2 minute ad for 20 second game – Peak - Brain Training Review

Can't speak for paid version but by the third time you play this game (first few times will play minimal ads to lure you in), you will have to watch 2-3 minutes of ads each time you play a game, some of which are literally 20 seconds. If you value your time and your life, I would stay away.
Review by naiwadesu on Peak - Brain Training.