This is a patch that's a long time coming, as it applies to the original Left 4 Dead on the Xbox 360. For those that purchased the Sacrifice DLC for the game, they may have found that it not only erased the progress of some other achievements - namely the Zombie Genocidist - but that certain achievements were unobtainable like one called Sacrifizzle. Thankfully, Valve have stood by their product and released a patch that fixes these glitches, restores the achievement progress for most people, and introduces a host of other tweaks and fixes.
The patch was actually released for the PC version back in October, so these fixes are already in place.
- In Versus mode Tanks will spawn in stasis until a human player takes over. Tanks in stasis are invisible and invulnerable, and won't move or attack.
- Tank speed is no longer reduced when on fire.
- Allow players on the Infected team to manually spawn during finales.
- Added a vote option to toggle All-Talk.
- Special Infected that causes a Survivor to stumble into a "ledge hang" situation will receive 50 points.
- Bullets that first pass through an infected character before striking a Survivor are now ignored as friendly fire.
- In Versus mode car alarms will now trigger anytime a Special Infected pulls or stumbles a Survivor into an alarm car.
- Survivor Bots no longer try to melee exploding barrels out of their way.
Anyone planning on firing this one up now to wrap up some achievements?
Source: Trueachievements.com