Balloon Fight from the NES era is currently on the Wii U Virtual Console for a bargain $0.30. This has obviously lured gamers into parting with their cash, as it sits proudly atop the current charts.

Wii U eShop
1. Balloon Fight
2. The Cave
3. Little Inferno
4. Trine 2: Director's Cut
5. Mighty Switch Force: Hyper Drive Edition
6. Nano Assault Neo
7. New Super Mario Bros. U
8. Sonic & All-Stars Racing Transformed
9. Scribblenauts Unlimited
10. ZombiU
11. Assassin's Creed III
12. Darksiders II
13. Chasing Aurora
14. Funky Barn
15. Batman: Arkham City Armoured Edition
16. Ninja Gaiden 3: Razor's Edge
17. Tekken Tag Tournament 2
18. Just Dance 4
19. Warriors Orochi 3 Hyper
20. Marvel Avengers: Battle for Earth

3DS eShop
1. Pokemon Dream Radar
2. Super Mario Bros
3. Gunman Clive
4. Pokedex 3D Pro
5. Super Mario Bros: The Lost Levels
6. Tetris
7. Mega Man
8. Punch Out
9. The Legend of Zelda: Link's Awakening DX
10. Cut The Rope
11. Photo Dojo
12. Super Mario Land 2: 6 Golden Coins
13. 3D Classics Kirby's Adventure
14. Bird Mania 3D
15. The Legend of Zelda
16. Plants vs. Zombies
17. Kirby's Star Stacker
18. Crimson Shroud
19. Super C
20. Colors! 3D