Almost certainly Mutant, a Gamma World ripoff using a BRP-like system. At the time, the main Swedish RPG company had three different RPGs being published: Drakar och Demoner, Mutant, and Chock (translated version of Chill), and a classmate's brother and his friends had divided things up so they had one each.
Moldvay Basic D&D. I was introduced to gaming through AD&D but could only get the Basic set in local stores... so we switched over to that until we could get the AD&D books.