I'm not going to dance around this: I think Dr. Mario is tons more fun than Tetris! Sure, Tetris is great and all; it has superb music, and the concept is simple yet ingenious. But when Mario tosses on the white coat and stethoscope, all bets are off. Dr. Mario is insanely entertaining, and the music is good enough to leave on in the background even when you're NOT playing, just for ambient sound. When I found out you could play as Dr. Mario is Super Smash Bros. Brawl, I think I had an ecstasy aneurism.
Even moms like this game! Listen to this raving testimonial by the harshest video game critic of all, my mom: "Oh, Dr. Mario! I love that game!" See?