The PIXELearning blog profiles the ATC21S project–a multi-stakeholder research project sponsored by Microsoft, Intel, and Cisco. The project aims to develop ways of assessing 21st-century skills, with the aim of creating tools to support skills that critically underpin subjects such as science, math, and reading. Serious gaming is one of the tools under exploration, and PIXELearning has been working with the project team to create a multiplayer game designed to promote collaborative problem-solving skills.