ToC Figure. The Dynamic Optical MicroEnvironment (DOME) enables closed-loop spatio-temporal control of microscopic collectives (e.g. microrobots, microparticles, algae, bacteria, or mammalian cells) using light. The DOME is low-cost, open source and easy to build using off-the-shelf components. Results show Volvox algae displaying desired augmented capabilities, including communication, stigmergy, and motion control, essential for future cooperative behaviours.