GfK ChartTrack reports that Halo: Reach has entered the All Formats All Prices UK video game chart at No.1, recording Microsoft's biggest ever launch week and the fifth biggest launch ever in the UK.
Halo: Reach's debut week is behind Modern Warfare 2 on Xbox 360 and PS3, Grand Theft Auto: San Andreas on PS2 and GTA4 on Xbox 360.
Despite the huge increase in installed base, Halo: Reach could only improve on Halo 3's launch week by 20,000 sales, but did eclipse Halo 3: ODST by nearly 200,000 units.
Sony's PlayStation Move title, Sports Champions, is a new entry at No.2, while Mafia II is demoted to No.3.
The rest of the PlayStation Move launch line-up couldn't match the success of Sports Champions, with Start the Party! At No.29 and Ubisoft's Racket Sports at No.32.
The week's only other new entry is EA's NHL 11 at No.26.
Look out for a flurry of new releases this week - Dead Rising 2, F1 2010, Quantum Theory, Final Fantasy XIV, Civilization V, Darksiders (PC) - but will anything be able to topple Halo?
Leisure software charts compiled by Chart Track, (C)2010 UKIE Ltd (All Prices) Week 37, 2010
1. HALO: REACH
2. SPORTS CHAMPIONS
3. MAFIA II
4. TOY STORY 3
5. PRINCE OF PERSIA: THE FORGOTTEN SANDS
6. TOM CLANCY'S H.A.W.X. 2
7. KANE & LYNCH 2: DOG DAYS
8. JUST DANCE
9. TIGER WOODS PGA TOUR 11
10. RED DEAD REDEMPTION
12. SUPER MARIO GALAXY 2
13. SPIDER-MAN: SHATTERED DIMENSIONS
14. NEW SUPER MARIO BROS.
15. LEGO HARRY POTTER: YEARS 1-4
16. MASS EFFECT 2
17. WII FIT PLUS
18. WII SPORTS RESORT
19. BATTLEFIELD: BAD COMPANY 2
20. TETRIS PARTY DELUXE