iThrive Sim is a digital platform that powers and assesses playful, embodied social and emotional skill-building experiences for teens. Play is steered by teens’ improvised interactions and real-time decisions, impacting each game’s story. iThrive Sim’s tech enables the modulation of stress experienced by each player and monitors in-game behaviors taken in response. Its next iteration, made possible by the Learning Engineering Tools Growth Award, will expand the platform’s data collection and assessment capabilities with pre- and post-reflection features that enable students who play iThrive Sim games and the educators who facilitate them to generate valuable data on teens’ real-time social and emotional functioning and skill development.