Game-based learning has been shown to promote active learning. We have designed a card game termed CountQuest, played on the online platform Zoom, to facilitate the revision of the effective atomic number (EAN) concept for metal complexes previously taught in lectures. This game was played by undergraduate and graduate chemistry students during their respective 1 h tutorial sessions. The efficacy of the intervention was shown using pre/post surveys. The results of our activity demonstrate that judiciously designed card games can be used to improve teaching of key concepts in inorganic chemistry at both undergraduate and graduate levels.