This study examined a game-based teaching activity on "Factors and Multiples" designed for the 6th grade students. The game aims to create a differentiated and enriched learning environment targeted the curriculum standard "The students determine prime numbers using their properties. The students find prime numbers using the Eratosthenes sieve method." The game was played within two-course hours with 22 gifted students attending a Science and Art Center in Turkey. The students' learning behaviors were observed with an observation form during the game. At the end of the lesson, students were given a semi-structured interview form to get their opinions on the use of games in mathematics lessons. It was observed that the students were enthusiastic and were having fun during the game. The students explained that the game was both educational and entertaining and they expressed their wishes for more game activities to be included in the lessons.