Agent-based modeling is increasingly popular for studying complex systems. However, it requires significant computer programming work because it involves describing all agents and their behaviors in the form of algorithms. The GAMA open-source platform aims to assist modelers with this task. Developed since 2007 by a consortium of research teams, this versatile platform allows model content to be built using an accessible modeling language and then simulated. GAMA has seen significant growth in recent years due to its ability to create and simulate large-scale models, including those with hundreds of thousands of agents and detailed geographic data. It also features advanced 3D visualization tools and tools dedicated to the construction of serious games. This platform is now used in numerous research projects addressing diverse issues such as epidemiology, land-use change, natural or technological risks, natural resource management, and urban mobility.