In this paper we report on the first year of an online competition in which 480 students took part. After a brief presentation of the organizational structure of the marathon and general data about students' participation, we discuss findings from questionnaires about participants' attitudes towards mathematics, technology, and their perception of the experience. We focus on the two following questions: (1) How can more students be attracted to mathematics by means of competitions?; and (2) How do students perceive their participations in such events? In addition, we analyse several examples of challenging tasks solved by participants and their contributions to the online Discussion Forum. Our data does provide us with better insight into how this experience extends mathematics learning beyond the classroom by means of informal opportunities, such as competitions.