We investigated the transfer of training of a stand-alone educational serious game supported with automated feedback and instruction compared to conventional on-the-job training (OJT). If transfer of training is sufficiently high, these types of games could reduce time-consuming and expensive OJT saving instructional personnel. In a case study with such a game, the CASHIER TRAINER supported with an ITS, we compared performance and competence of new cashier employees at the workplace in two matched groups: (a) experimental group: acquiring cashier skills in the game CASHIER TRAINER; (b) control group: acquiring cashier skills in conventional OJT. Performance and competence were measured by observation and by selfassessment. The results showed that performance and competence were at least as high and even higher on certain aspects for the CASHIER TRAINER than for the OJT condition. Thus, transfer of training with the CASHIER TRAINER was positive in comparison with OJT. Specifically, non-regular tasks which could be trained with gaming more often and structured than in OJT were performed better. It seems that automated feedback in stand-alone educational serious games for procedural tasks, if well-designed, could replace human tutoring to a certain extent.