Games are voluntary activities that provide enjoyable experiences for many people around the world. It has been proven necessary for the first hour of play, referred to as the onboarding phase, to be able to provide a positive experience in order to prevent players from prematurely leaving the game permanently. This study explores the use of heuristic evaluation as a tool for assessing the onboarding phase while aiming to improve current practice by considering the onboarding phase as a learning experience in addition to its connection with enjoyability and engagement. To find answers, pre-existing onboarding heuristics was evaluated through practical use during heuristic evaluation of 10 different games and reformulated by comparing evaluation findings and literary review discoveries. This resulted in a set of onboarding heuristics with a more supportive and coherent sense that could be considered a more suitable tool for heuristic evaluation of the onboarding phase.