Over the past several decades, there has been much interest regarding the effects of video game play. Research has evaluated the behavioral, cognitive, and psychological effects of video game play, and found individuals who play games using complex and dynamic game settings and require focused attention with quick responses, such as action video games, demonstrate improved cognitive performance. Action video game training has also yielded rehabilitation efficacy for a myriad of patients, such as stroke patients and individuals with vestibular and balance deficits. Recently, new technology platforms have been developed such as mixed reality (MR); however, little to no research has been conducted examining the effects of advanced technology platforms. The purpose of the current study was to explore whether MR game training improved visuo-motor reaction time and balance performances. Fourteen participants (11 male; 18–50 years of age) underwent baseline and post-intervention assessments, and then complete 8 h of MR action game training. Visuo-motor reaction times were obtained via computerized Automated Neurocognitive Assessment Metric testing and balance measures were obtained via Sensory Organizational Testing. Baseline and post-intervention comparisons were analyzed using Wilcoxon signed-rank tests. Baseline and post-intervention visuo-motor reaction time and balance comparisons revealed that MR game training yielded significant reaction time improvements (p < 0.05) and vestibular performances (p < 0.05) following game training. Our results suggest visuo-motor reaction time and balance performances were significantly improved following of 8 h of action MR game training.