Major Nelson has revealed some data for Xbox Live and Games for Windows Live in terms of Unique Users and titles purchased for their games.
On the retail front, 13 of the top 20 games for 2009 had some form of co-op in it. Granted, two of those are the same game, Resident Evil 5, but one is the Japanese version called BioHazzard. The Call of Duty franchise did particularly well with 3 of the top 5 games coming from that franchise. Of course World at War and Modern Warfare 2 are the ones on our radar thanks to co-op.
In terms of purchases, XBLA didn't fair as well with only 5 of the 20 most purchased games last year having some form of co-op. Halo 2 is still dominating the Xbox 1 charts, though the game only has local co-op. Finally on the Games for Windows side of the fence, GTA IV dominated with it's small co-op mode, but #2 is the great Dawn of War 2 which we found most excellent. Also listed are Indie games, which we currently don't track - but probably should.
All in all a good year for co-op gamers on Microsoft's platforms.
Xbox 360 Top Live Titles (based on unique users)
1 Halo 3
2 Call of Duty 4
3 Modern Warfare 2
4 Call of Duty: WaW
5 Gears of War 2
6 GTA IV (Purchase and download the full game)
7 Left 4 Dead
8 Halo 3: ODST
9 FABLE II Episode 1 (of 5)
10 BioHazard 5 (Resident Evil 5)
11 Halo Wars - Demo
12 RESIDENT EVIL 5
13 Fallout 3
14 UFC 2009 Undisputed Demo
15 Left 4 Dead 2 - Demo
16 Gears of War
17 1 vs 100
18 Guitar Hero World Tour
19 Guitar Hero III
20 FIFA 09
Top Arcade Titles (full versions purchased)
1 Battlefield 1943
2 Castle Crashers
3 Trials HD
4 Hasbro Family Game Night **
5 Shadow Complex
6 Marvel vs. Capcom 2
7 Magic: The Gathering
8 UNO
9 Worms
10 Peggle
11 Worms 2: Armageddon
12 Turtles in Time Re-Shelled
13 'Splosion Man
14 A Kingdom for Keflings
15 3 on 3 NHL Arcade
16 The Secret of Monkey Island: Special Edition
17 Teenage Mutant Ninja Turtles 1989 Classic Arcade
18 Marble Blast Ultra
19 Ultimate Mortal Kombat 3
20 Super Street Fighter II Turbo HD Remix
**Combined sales of all Hasbro Family Game Night titles
Top Original Xbox Titles (based on unique users)
1 Halo 2
2 Star Wars: Battlefront 2
3 Fable
4 Counter-Strike
5 Conker: Live Reloaded
6 Doom 3
7 Splinter Cell Chaos
8 SW: KOTOR
9 Star Wars: Battlefront
10 SW: Republic Commando
11 Burnout 3
12 Fable: Lost Chapters
13 Call of Duty 2
14 Call of Duty 3
15 Call of Duty Finest
16 MechAssault 2
17 Crimson Skies
18 Guilty Gear XX #Reload
19 Rainbow Six 3
20 Gauntlet Seven Sorrows
Top Indie Games (full versions purchased)
1 I MAED A GAM3 W1TH Z0MB1ES!!!1
2 Avatar Drop
3 RC-AirSim
4 Headshot
5 Miner Dig Deep
6 Rumble Massage
7 Who Did I Date Last Night
8 Kodu Game Lab
9 Avatar Golf
10 Aquarium HD
11 myFishtank
12 Head Shot 2
13 DrumKit
14 A Perfect Massage
15 The Impossible Game
16 Inside Lacrosse's CL2010
17 ZP2K9
18 ezmuze+ Hamst3r edition
19 The Drinking Game
20 Physics Sandbox
Top Games For Windows LIVE (based on unique users)
1 GTA IV
2 Warhammer 40,000: Dawn of War II
3 Fallout 3
4 Shadowrun
5 Street Fighter IV
6 Halo 2 (PC)
7 Batman: Arkham Asylum
8 Resident Evil 5
9 Gears of War (Windows)
10 Red Faction Guerrilla
11 Battlestations: Pacific
12 Kane & Lynch: Dead Men
13 DiRT 2
14 Section 8
15 Quantum of Solace PC
16 FlatOut UC (PC)
17 Fuel
18 Viva Piñata
19 SWTCW: Republic Heroes
20 Juiced 2: HIN
Source: Majornelson.com