This game basically put me in touch with grief in the chillest way possible, and helped me deal with it when I had to experience it for real. When I couldn't find all the emeralds, and Sonic runs through the zones to the bittersweet ending music, then eventually sees his buddy Tails in the stars - I broke down.
My parents had to help me through it. I was really young and never expected such a fun game to make me feel so many things all at once. Loved it - made me a Sonic fan for life!