Could you link to these sales figures?
Since sales figures are hard to find unless you archive them, the best I can do is show this:
1. (DS, Pokemon) Pokemon Diamond - 123,573 / 2,119,848
2. (DS, Pokemon) Pokemon Pearl - 97,409 / 1,766,776
3. (DS, Nintendo) Kirby Squeek Squad - 92,173 / 557,634
4. (DS, Sega) Fushigi no Dungeon: Furai no Shiren - 88,242
5. (DS, Nintendo) New Super Mario Brothers - 77,761 / 3,617,021
6. (DS, Sega) Love and Berry DS Collection - 72,841 / 608,545
7. (DS, Nintendo) Jump Ultimate Stars - 71,339 / 349,979
8. (PS2, SCE) Wild Arms 5 - 70,476
9. (Wii, Nintendo) Wii Sports - 69,923 / 318,473
10. (Wii, Pokemon) Pokemon Battle Revolution - 67,607
Pokemon DP total: 220,982 / 3,886,624
11. Common Knowledge Training
12. Wii Play
13. Animal Crossing Wild World
14. Yakuza 2
15. Recipe 1000 DS
16. Puyo Puyo!
17. Gundam SEED DESTNY Federation vs ZAFT II PLUS
18. More Brain Age
19. Naruto Shinobi Retsuden
20. Ryuusei no Rockman Pegasus
21. Jikkyou Powerful Pro Baseball 13 Ketteiban
22. World Soccer Winning Eleven 10 Ubiquitous Evolution (PSP)
23. Ryuusei no Rockman Dragon
24. MAPLUS Portable Navigator
25. 200 Mannin Kanji
26. Ryuusei no Rockman Leo
27. Mario Kart DS
28. Yakuza (PS2 The Best)
29. Momotarou Dentetsu 16
30. Brain Age
Being #12. doesn't seem like much, unless you consider that this is more than a year after its release.
And more than two years after?
01./02. [WII] Wii Fit (Nintendo) - 149,587 / 411,000
02./06. [NDS] Mario Party DS (Nintendo) - 106,995 / 646,000
03./00. [NDS] Tales of Innocence (Bandai-Namco) - 104,317 / NEW
04./00. [PSP] Hot Shots Golf Portable 2 (Sony) - 87,231 / NEW
05./01. [NDS] Prof. Layton and Pandora's Box (Level 5) - 75,609 / 370,000
06./04. [NDS] Dragon Quest IV (Square-Enix) - 63,447 / 795,000
07./00. [360] Lost Odyssey (Microsoft) - 54,581 / NEW
08./00. [NDS] Powerful Pro-kun Pocket 10 (Konami) - 54,372 / NEW
09./11. [WII] Super Mario Galaxy (Nintendo) - 44,705 / 476,000
10./09. [WII] Mario and Sonic at the Olympic Games (Nintendo) - 44,677 / 148,000
11./03. [PS2] SD Gundam G Generation Spirits (Bandai-Namco)
12./07. [PS2] World Soccer Winning Eleven 2008 (Konami)
13./00. [NDS] Gintama: Gintama Quest: Gin-san Changes Jobs to Save the World (Banpresto)
14./14. [WII] Wii Sports (Nintendo)
15./15. [WII] Wii Play (Nintendo)
16./05. [PS2] Sengoku Basara 2: Heroes (Capcom)
17./00. [PSP] Yuusha no Kuse ni Namaiki da (Sony)
18./00. [NDS] Nep League DS (Jaleco)
19./00. [PSP] Silent Hill Zero (Konami)
20./19. [WII] Mario Party 8 (Nintendo)
21./12. [PS3] World Soccer Winning Eleven 2008 (Konami)
22./27. [NDS] Pokémon Mysterious Dungeon: Time Expedition Party (Pokémon)
23./23. [NDS] Mario Kart DS (Nintendo)
24./00. [PS3] Uncharted: Drake's Fortune (Sony)
25./00. [NDS] MySims (EA)
26./00. [PS2] Yakuza 2 (Sega)
27./29. [NDS] New Super Mario Bros. (Nintendo)
28./31. [NDS] Pokémon Mysterious Dungeon: Shadow Expedition Party (Pokémon)
29./00. [PSP] Grand Theft Auto: Vice City Stories (Capcom)
30./00. [NDS] Haneru no Tobira DS: Short-Line Railroad Night (Bandai-Namco)
31./24. [NDS] Prof. Layton and the Curious Village (Level 5)
32./10. [NDS] Yu-Gi-Oh! Duel Monsters World Championship 2008 (Konami)
33./00. [PS2] Grand Theft Auto: Vice City Stories (Capcom)
34./18. [NDS] My Housekeeping Diary (Nintendo)
35./37. [WII] Wario Ware Smooth Moves (Nintendo)
36./00. [360] Virtua Fighter 5 Live Arena (Sega)
37./16. [PS3] Shin Sangoku Musou 5 (Koei)
38./00. [WII] No More Heroes (Marvelous Entertainment)
39./34. [NDS] Taiko Drum Master DS (Bandai-Namco)
40./22. [WII] Resident Evil: Umbrella Chronicles (Capcom)
41./20. [NDS] Mega Man Star Force 2: Berserk × Dinosaur (Capcom)
42./28. [NDS] Flash Focus: Vision Training in Minutes a Day (Nintendo)
43./39. [NDS] Kanji Brain Test 2.5M (IE Institute)
44./21. [NDS] Mega Man Star Force 2: Berserk × Shinobi (Capcom)
45./25. [NDS] Dinosaur King: The Seven Fragments (Sega)
46./43. [NDS] Animal Crossing Wild World (Nintendo)
47./49. [NDS] Tamagotchi no Puchi-Puchi Omisecchi: Thanks Everybody! (Bandai-Namco)
48./35. [NDS] Won!tertainment: Music Channel (Capcom)
49./42. [NDS] More Brain Age (Nintendo)
50./38. [PSP] Monster Hunter Portable 2nd (Capcom)
#46.
It sold 1 million copies in three weeks in Japan alone. Its LTD (life-to-date) sales in Japan alone are in excess of 4.5 million copies sold. In PAL regions, it's sold more than 2 million copies. In America, it's sold more than 1.5 million copies.
ACWW is one of the most successful video games in the history of the industry. 8 million is
nothing to sneeze at. Metroid may have a large fanbase and many, many great games, but it's definitely one of Nintendo's less successful major franchises.