You can either select a specific category, or play “All” that is a randomized mix of tests and questions from all four categories.
In the game preferences you will find some very useful and important factors that can be tuned to your liking.
If you are colorblind for example you can set gbrainy to skip puzzles that use colors. You can also choose one of the two available themes, set the memory questions timer, the game difficulty, and setup player’s game session history.
Let me show you some puzzles of all four categories to get an idea of what is going on. Press images for larger.
After you have finished all puzzles you can see how well it went and examine the diagrams to determine your weak and strong categories.
You will most likely find gbrainy in your distribution default repositories, but if you want the latest version 2.1.4 you can download and compile it from here.