The LEGO Batman sequel falls down to third, behind The Amazing Spider-Man, which remains second.
Elsewhere, FIFA Street climbs from ten to five, above FIFA 12 and Modern Warfare 3, the latter jumping from 20 to seven.
Propping up the chart is Sniper Elite V2, which climbs two places to re-enter at ten.
The top ten in full:
1. (3) London 2012: The Game (Sega)
2. (2) The Amazing Spider-Man (Activision)
3. (1) LEGO Batman 2: DC Super Heroes (Warner Bros Interactive)
4. (4) Spec Ops: The Line (2K Games)
5. (10) FIFA Street (Electronic Arts)
6. (6) FIFA 12 (Electronic Arts)
7. (20) Modern Warfare 3 (Activision)
8. (7) Elder Scrolls V: Skyrim (Bethesda Softworks)
9. (5) Ratchet & Clank Trilogy (Sony)
10. (12) Sniper Elite V2 (505 Games)
Leisure software charts compiled by Chart Track, (C) 2012 UKIE Ltd.
Watch a trailer for London 2012: The Official Video Game below: