Sega's Olympic simulation comfortably beats Batman: Arkham City into second and Elder Scrolls V: Skyrim into third.
At the tail-end of the chart, Uncharted 3: Drake's Deception manages to re-enter at nine, ahead of an imminent update packed with fixes, enhancements, Trophies and game modes.
The top ten in full:
1. (1) London 2012: The Game (Sega)
2. (3) Batman: Arkham City (Warner Bros Interactive)
3. (7) Elder Scrolls V: Skyrim (Bethesda Softworks)
4. (2) LEGO Batman 2: DC Super Heroes (Warner Bros Interactive)
5. (4) The Amazing Spider-Man (Activision)
6. (5) Modern Warfare 3 (Activision)
7. (13) Battlefield 3 (Electronic Arts)
8. (6) Ghost Recon: Future Soldier (Ubisoft)
9. (12) Uncharted 3: Drake's Deception (Sony)
10. (8) Max Payne 3 (Rockstar)
Leisure software charts compiled by Chart Track, (C) 2012 UKIE Ltd.
Watch a trailer for London 2012: The Official Video Game below: