Complex sentence: Six different scoring levels are defined (level 1-5 are denoted by platonic solids and level 6 is denoted by sphere), plus a special Eulerians level that contains the members who have solved at least half of the most recent 25 problems.
Split into simpler sentences: Six different scoring levels are defined (level 1-5 are denoted by platonic solids and level 6 is denoted by sphere). A special Eulerians level exists for members who have solved at least half of the most recent 25 problems.