Game Theory models a rational decision-making process where economic agents are pure utility-maximizing beings (Schelling, 1980). However, in many relevant Games, humans act and decide di↵erently in real-world experiments than Modern Game Theory would predict (Rabin, 1994). This discrepancy is seen in the Ultimatum Game (UG) (Guth, Schmittberger, and Schwarze, 1982) and raises discussions on how Emotions, Culture and Morals influence the decision-making process. The UG is also a simple and easy-toreplicate experiment - with over 1,000 pieces of related literature. This paper aims to discover via Systematic Literature Review (SLR) trends and gaps of knowledge in the study of the UG. We found that perceived fairness by players is the main driver of variations in behavior - and that many factors aect perceived fairness (including but not limited to comparison to peers; gender; culture; hormonal levels; sense of legitimacy amongst players). Throughout this analysis, the main motor theme found is Bioeconomics, potentialized by the emergence of the field of Neuroeconomics. In contrast, the degree of integration between this field and classic economics is questioned, as per our keywords co-occurance analysis: three distinct clusters were found. Two of them, comprising of themes related to Bioeconomics, are considerably less connected to clusters in Traditional Game Theory. Finally, it was found that there is no consensus to thoroughly explain Player 1 s psychological rationale in an UG. Based on our findings, we propose an UG variation, the Broker Game, to improve upon deficiencies and limitations of the original UG and eventually allow for a postulation of a emotional-rational decision-making model.