If you want to become Dr Brain's new helper (and you want if you are playing this) you have to solve all the puzzles that wait on his castle, placed to test your skills resolving problems of all kinds.
Most of them are classics, like remembering the order of a melody that becomes more complex each time you repeat it successfully, or the magic squares, those horrible puzzles where you must sort numbers until all the summations of columns, rows and diagonals have the same value.
Along them you get some interesting ones, such as programming a robot to get objects from a labyrinth, with the additional nuisance of having three heads for it: one works well, one never does what it is told and the third sometimes obey, sometimes not. It's not hard to spot the good one but don't get happy, if you try a harder difficulty each head will broke after getting each object.
You can change whenever you please the difficulty level, there are three and some of the puzzles get changes with each of them. Sadly a few are always the same, which can get boring when replaying.
Anyway if you want to quickly solve a puzzle you can use the hint system, if you pay. Each time a puzzle is solved you get a hint coin, pressing on the coin slot button each of the puzzles have will expend one of them and get you some help. A few times (this includes copy protection by the way) it won't help you but solve the puzzle
A bit of trivia, this game is uses the well known Sierra's graphic adventure engine. It matters little, as the times you use objects from the inventory it is for things like opening a door. And the interaction with the surrounding is really small. You can't criticize the game for it, after all this is about going from puzzle to puzzle, but it would have been a nice touch adding more things to the surroundings.