Garry's mod just got an update with 15 Steam Achievements.
 
And here they are:

• Play Singleplayer - Play singleplayer at least once
  
• Play Multiplayer - Play multiplayer at least once
  
• Startup Millennium - Start Garry's Mod 1000 times
  
• Secret Phrase - Say the secret phrase
  
• Addict - You have wasted a year of your life playing Garry's Mod!
  
• Map Loader - Play 20 different maps
  
• Play Around - Play a gamemode that isn't sandbox
  
• Friendly - Play around with 10 friends
  
• are you the real garry? - Play on the same server as garry
  
• Marathon - Play on the same server map for 8 hours
  
• One Day - 24 hours of your life wasted
  
• One Week - One whole week of your life wasted
  
• One Month - One whole month of your life wasted
  
• Half Marathon - Play on the same server map for 4 hours
  
• Killed 1000 Baddies - Kill 1000 Baddies

Haven't there been achievements for Gary's Mod for a while now? Not official ones, ones you could download off the internet?

Ouch. Some of those are quite involved. Who doesn't like a challenge tho.

Meh, I would have got them all, if they existed when I bought the game. ;I

" @Satune: Yeah, but official ones are way better. Those achievements were largely irrelevant; these official achievements will probably get me to play Garry's Mod more often. "

I may or may not have accidentally left gmod running over night to get Marathon.

" I may or may not have accidentally left gmod running over night to get Marathon. "

" @Jeff said:

" I may or may not have accidentally left gmod running over night to get Marathon. "

:|  Thanks for spilling the beans on that secret word achievment. Almost as easy as those 1550 achievment points I got out of Fallout 3. "

" @Scooper said:

" @Jeff said:

" I may or may not have accidentally left gmod running over night to get Marathon. "

:|  Thanks for spilling the beans on that secret word achievment. Almost as easy as those 1550 achievment points I got out of Fallout 3. "

Wait, what? how did he spill the beans on the secret word achievement? "

Two weeks later, 10 new achievements!
 

• Innocent Bystander – Kill 1000 innocent animals
• Ball Eater – Eat 200 balls
• Creator – Spawn 5000 props
• Popper – Burst 1000 balloons
• Destroyer – Remove 5000 things
• Menu User – Open the spawnmenu 100,000 times
• Bad Coder – Experience 500 Lua programming errors
• Procreator – Spawn 1000 NPCs
• Dollhouse – Spawn 2000 ragdolls
• Bad Friend – Kill 1000 friendly NPCs