View of rational choice in coherence with ultimatum game. Rational choice theory adjusted by joining behavioral economics to better comprehend decision-making processes. In this thesis I focus on researching strong influences using multiple simple games. Namely: ultimatum game, dictator game and modifications of previous. They will be carried out by online questionnaire. Next step will be analysis of components to determine significant ones and impact of game's modifications. I assume that decision-maker's rationality will be disproven. This thesis will continue with assessing influence of risk and fear of loss. Goal is to gather enough of detailed data about motivations and participants in order to perform analysis and establish statistically significant influences.