This paper first presents a critical analysis of an existing game (APEX), designed by researchers in psychoacoustics only, to measure psychoacoustic thresholds in preschoolers. Next it presents another game (DIESEL-X), designed by dyslexia researchers and game designers, to remediate the shortcomings of the former game. Via a repeated measures experiment (n = 95), the game experience, attention, and psychoacoustic thresholds are compared. It is shown that the children prefer the game experience of DIESEL-X over APEX. Moreover, the former game was able to measure lower frequency-modulation thresholds than APEX. These results demonstrate that when it comes down to game-based assessment of children's perceptual capabilities, the quality of game design not only has an effect on game experience, but equally on the scientific measurements obtained via such a game-based assessment.