Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that can alter the excitability of targeted brain regions and influence motor learning. This study investigates the effects of concurrent M1 anodal and cerebellar cathodal tDCS (M1a+CBc) on motor learning in a complex rhythm-timing video game task. Forty-two participants practiced the game with their non-dominant hand while receiving either M1a+CBc (n = 24) or sham tDCS (n = 18). Performance was assessed using a performance index (PI) incorporating keystroke timing accuracy, tap distribution ratio, and key error rate. A 2 x 5 mixed ANOVA revealed a significant main effect of stimulation group on PI gain scores across practice blocks (P = 0.021, ηp2 = 0.126), with M1a+CBc showing greater gains than sham. An ANCOVA, controlling for baseline performance, showed that the M1a+CBc group had significantly higher post-test PI scores compared to the sham group (P = 0.034, ηp2 = 0.110). These results suggest that concurrent M1a+CBc tDCS significantly enhances motor learning in complex tasks.