Neurodevelopmental disorders like ADHD can affect rhythm perception and production, impacting performance in attention and sensorimotor tasks. Improving rhythmic abilities through targeted training might compensate for these cognitive functions. We introduce a novel protocol for training rhythmic skills via a tablet-based, serious game called Rhythm Workers (RW). This proof-of-concept study tested the feasibility of using RW in children with ADHD. We administered an at-home longitudinal protocol across Canada. A total of 27 children (7 to 13 years) were randomly assigned to either a finger-tapping rhythmic game (RW) or a control game with comparable auditory-motor demands but without beat synchronization (active control condition). Participants played the game for 300 min over 2 weeks. We collected data (self-reported and logged onto the device) on game compliance and acceptance. Further, we measured rhythmic abilities using the Battery for the Assessment of Auditory Sensorimotor and Timing Abilities (BAASTA). The current findings show that both games were equally played in duration, rated similarly for overall enjoyment, and relied on similar motor activity (finger taps). The children who played RW showed improved general rhythmic abilities compared to the controls; these improvements were also positively correlated with the playing duration. We also present evidence that executive functioning improved in those who played RW, but not in the controls. These findings indicate that both games are well matched. RW demonstrates efficacy in enhancing sensorimotor skills in children with ADHD, which may benefit their executive functioning. A future RCT with extended training and sample size could further validate these skill transfer effects.