What is Dynamic Difficulty Adjustment (DDA)

Serious games have been used for assisting people in physical rehabilitation for hands. People might have different degrees of mobility in their hands; consequently, it would be convenient that the game could be adapted according to the range-of-motion in performing hand movements. This study implemented a serious game for hand rehabilitation with two play modes. Mode one does not adjust the game difficulty; whereas mode two adjusts the game difficulty according to the player's range-of-motion in performing flexion, extension, ulnar, and radial deviations. The game difficulty was adjusted using fuzzy logic to compute positions at which the rewards will be displayed at the game scene (easy, medium, and difficult positions to collect the rewards). Four participants played both modes. Two-tailed t-tests revealed that there were no significant differences between both modes in terms of rewards collected (p = 0.6621), play time (p = 0.8178), and “game engagement questionnaire” score (p = 0.1383).