WIP: light-blue theme
This theme is based on Color Psychology: The Complete Guide for Marketers by Nick Kolenda. I have chosen the colors with the help of the following table.
By counting the ticks for each color within the highlighted lines, blue was the "winning" color, meaning it gained the most ticks. Besides, the table says, that both high value and high chroma will fit best for the selected attributes.
The chosen attributes describe a theme, which is exciting and gains attention of the user. Furthermore it is designed to play quick (utilitarian) quizzes. These facts induced me to take a light blue as primary color and a dark orange as the secondary color for that it has enough contrast.