Gamification is widely used in sports to enhance individual performance. In team sports, however, where social interaction and collective success matter, the use of game mechanics to encourage team interaction–known as social gamification–remains underexplored, despite its potential to foster collaboration and cohesion. This study examines how social gamification supports group dynamics, i.e., cohesion, social identity, and enjoyment in team sports, while addressing challenges like social loafing. Therefore, we developed a gamification app for soccer teams with two designs: First, a cooperative setting with team challenges and a virtual mascot; Second, a cooperative-competitive design adding a leaderboard for intra-team competition. These were tested in two four-week field experiments involving 119 participants. Results reveal that cooperative gamification fosters enjoyment, social identity, and aspects of cohesion, while intra-team competition does not harm group dynamics and actually promotes enjoyment. These findings highlight the effectiveness of social gamification and inform practical design strategies.