I do it a little differently; I'll encounter a smell and then try to associate it with a game character. For example, I reckon Mega-Man smells like a mechanic's workshop- axle grease and hot steel. Link smells like fresh earth and water with a faint hint of blood. De Blob smells like wet paint. Sackboy smells a little bit musty, combined with the smell of an arts and crafts room.