The aim of this study was to test whether an online video game can be used to investigate planning ability and whether fluid intelligence, objective numeracy, and subjective numeracy are predictive of game performance. Our results demonstrate that fluid intelligence is particularly important, which is in line with previous non-game-based studies that show a relationship between classical planning tests and fluid intelligence. Video games have been previously used for research into cognitive processes and taking them online facilitates data collection on (...) a larger scale. Online video games also afford data collection without the expense and stress of a laboratory environment. For these reasons, using online video games to investigate human cognition is a promising alternative to the classic cognitive paradigms used in laboratories. (shrink)