Our study aims to assess brand-game congruence, within an advergame, based on game rules and brand positioning and seeks to demonstrate that rules can enrich positioning and legitimize the practice. We conducted a 2 * 2 between-subject experiment, manipulating the congruence between brand positioning and game rules. Higher congruence led to the advergaming practice being perceived as more legitimate than in cases of low congruence. Consequently, higher perceived legitimacy resulted in more positive affective attitudes towards both the advergame and the brand, and only attitude towards the brand influenced purchase intention.