This is a simple but effective game that I use with Year 10 science classes to teach Big Bang Theory. The game focuses on the first few minutes after the Big Bang and is themed around nucleosynthesis. The intention of the game is to teach students how the abundance of H and He in the Universe provides evidence for the Big Bang Theory. In this game students shuffle a deck of cards containing protons and neutrons. They play cards in a random order into the middle of the table. When certain combinations of cards occur a successful collision takes place between subatomic particles and an atomic nucleus is formed. For example, a proton and neutron card stacked on top of each other indicates a deuterium isotope, two deuterium isotopes collide to form He, and so on. As the game progresses the Universe ages and “empty space” cards are added to the deck. This simulates an expanding Universe where collisions are less frequent and the rate of formation of nuclei slows down. Students then analyse their results and discuss why only small atoms formed during the Big Bang and why H and He are so abundant in our Universe. Through this activity students gain an appreciation of the very brief window in time where atoms were able to form during the Big Bang. They learn that the Universe is comprised primarily of H and He, and that this provides evidence for the Big Bang Theory. They learn that the Universe existed as a tiny, hot and dense soup of plasma that underwent rapid inflation and cooling. This resource is a rich task and differentiated for multiple levels of aptitude and interest. The files include card files that can be printed and cut out, instructions for playing the game, a student worksheet and model answers. I find it generally runs over 2 lessons, but can be shortened to be played in a single lesson if required.