College students learned how to design the roots, stem, and leaves of plants to survive in five different virtual reality environments through an agent-based multimedia educational game. For each student, the agent used personalized speech (e.g., including I and you) or nonpersonalized speech (e.g., 3rd-person monologue), and the game was presented via desktop computer (low immersion) or head-mounted display (high immersion). Across both levels of immersion, students who received personalized agent messages performed better on retention and problem-solving transfer tests. Although students reported higher levels of physical presence with high rather than low immersion, higher immersion did not lead to better performance on tests of retention or transfer. Students learn more deeply from computer-based simulation games when an on-screen agent speaks to them in a personalized style rather than a nonpersonalized style.