This thesis investigates the potential of The Sims 3 as a tool for incidental English vocabulary learning among young adult learners, drawing on theories of second language acquisition by Krashen (1981; 1982), incidental vocabulary learning by Gass (1999) and Hulstijn (2001), extramural English by Sundqvist (2009), and digital-based games in language learning by Sadoski (2005) and Prensky (2001). The study explores how simulation games can support second language (L2) development through engaging and contextualised experiences. It aims to answer three research questions, regarding (a) players’ report on their perceived vocabulary learning in L2 English through playing The Sims 3, (b) types of vocabulary frequently encountered in the game, and (c) the presentation of repetitive vocabulary in The Sims 3 that supports learning. Using a mixed-methods approach, data were collected via a questionnaire, interviews, a vocabulary recognition test, and lexical analysis of in-game content. The findings indicate that most vocabulary in The Sims 3 presents a beginner level and is often related to everyday life, careers, and interior design. Its repetitive and contextualized nature may enhance learners’ recognition and retention of English words. Although participants did not attribute their language learning primarily to gameplay, many reported increased curiosity and awareness of new words during the vocabulary test, indicating a potential for incidental vocabulary acquisition. The study concludes that simulation games like The Sims 3, when accompanied by specifically designed learning materials, hold promise as supportive tools in language education.