With their realistic animation, complex scenarios and impressive interactivity, computer simulation games might be able to provide context-rich, cognitively engaging virtual environments for language learning. However, simulation games designed for L2 learners are in short supply. As an alternative, could games designed for the mass-market be enhanced with support materials to allow students to enter and make use of them for learning? This classroom-based investigation looked into whether the best selling game "The SIMs"[TM] could be rendered pedagogically beneficial to university-level ESL learners by means of supplementary materials designed to meet criteria for CALL task appropriateness. The mixed-methods study found statistically significant improvements in vocabulary knowledge, as well as a generally positive reaction to the modifications among users. (Contains 7 tables, 1 figure and 2 notes.)