Game Stats and Achievements in Steam
Stats are a feature of the Steam Community. Various individual player statistics will be tracked by Steam while you play games, such as the amount of time you have spent playing. Stats are also collected for individual games like Team Fortress 2, Portal and Half-Life 2: Episode Two. You can find achievements under the stats for your games as well.
The Steam development team is still ironing out some of the bugs with the Steam stats and achievements.
If you notice that stats or achievements do not appear to be tracked, or previously attained stats and achievements are missing, that is a good sign that either stat tracking is temporarily down or that you may have an Internet connection issue. During this time, your stats and achievements may not be recorded. Unfortunately, that means they will not appear later when everything returns back to normal.
Occasionally there may be issues with attaining certain achievements - in these cases, you will need to wait for a patch addressing this problem in order to attain them.
Very rarely certain achievements will be reset or adjusted, typically following a patch that is intended to fix issues with that achievement.
In any cases where you are missing achievements, they unfortunately cannot be restored. You will need to re-attain achievements that have been lost.
If you are experiencing intermittent connection issues, please follow this guide.
Achievements are rewards for completing game objectives or performing pre-determined actions in a game. The Steam Community Overlay will notify you when you have unlocked an achievement in Steam. Your achievements can be viewed in the game's main menu or through the stats in the Steam Community.
If you do not receive the pop-up notifications in the Steam Community while you earn achievements, please follow this guide.
Achievements are not recorded while playing in Commentary Mode or when sv_cheats is set to 1. If you would like to ensure that your achievements are tracked correctly, please do not play your game in any of these modes.
If you earn achievements while playing in Offline Mode that are supposed to grant promotional items this will not work. You need to earn your achievements while online in order to receive the items correctly.
Unfortunately, achievements can not be reset at this time.