With the rapid growth of online gaming, phishing attacks — disguised as malicious links, in-game messages, fake in-app purchases, and cloned accounts — pose a growing threat to users' personal and financial data. This study designed and evaluated a Unity-based serious educational game aimed at improving users' ability to recognize such threats, and compared its effectiveness against traditional training (articles, PDFs, webinars) in a randomized, two-group experiment. Sixty active online-game users (18–35 years) were equally divided between the two training methods. Results showed that the serious-game group's correct-identification rate rose from 50.08% to 82.28% (a 64% improvement), significantly higher than the traditional group's increase from 51.57% to 64.47% (25% improvement), with a very large effect size (Cohen's d = 2.60). The game group also showed faster reaction times, higher decision confidence, and fewer errors. These findings indicate that interactive, feedback-driven serious games are markedly more effective than static instruction for cybersecurity awareness training, and can serve as a practical tool for protecting online-game users from real-world phishing threats.