A patch for Gears of War 2 was released on January 20, 2009. The patch fixed a number of multiplayer exploits and bugs, added new Achievements and tweaked the gameplay balance. The patch will be automatically downloaded and installed when users boot up Gears of War 2 while connected to Xbox Live. Some of the new Achievements require the Combustible Map Pack.
Patch Details
The most significant change this patch in this patch is a number of fixes for the exploits that have plagued Gears 2 online multiplayer with cheating and unfair play. As of this update, you can no longer melee or grenade tag other players through walls, hold a two-handed gun and a shield at the same time, make your shield invisible, make yourself invisible, among other things. Most significant glitches and exploits have been removed.
There are also a number of general gameplay changes that Epic has implemented to make the game more enjoyable in general. For example, the shotgun used to be extremely unreliable if you were hosting a match and there was significant lag. The patch tweaks the shotgun to be a lot more usable during high-latency situation.Kotaku: Gears of War 2 Update Arrives (January 21, 2009)
Epic has also balanced the gameplay slightly with this patch. The Flamethrower receives a boost and now has stopping power. Grenades, on the other hand, have become less powerful: they are now much easier to shoot off of surfaces and respawn less frequently, making them harder to abuse when used as proximity mines.