Added dark mode.
A few design improvements.
Dual N-Back is a brain training game. It has been scientifically proven that it enhances cognitive abilities, specifically the working memory.
There will be a sequence of visual and audio stimuli, and the task consists of indicating when the current stimulus matches the one from n rounds earlier. The game will start with level 1, n=1, where you have to remember the position (square) and the sound (letter) of the stimuli from the previous round (one turn back).
Once the position or sound matches the one from n turns back, press the visual button, respectively the sound button.
Then, if there are less than 3 mistakes, the level will raise to 2, n=2, where you have to remember the position and sound 2 turns back, and so on.
