Play singleplayer This achievement doesn't even need to be explained, everything is clear, you just need to play the singleplayer

Play multiplayer Just go to any server

Play aroundGo to any server that is not a sandbox

Ball eater
To get this achievement you just need to spawn 200 balls and eat them. I recommend making them into some closed achievement and eating them in one go.
Creator
You just need to spawn 5000 objects.
Destroyer
You just need to remove 5000 object
Procreator
You must spawn 1000 NPCs.
Dollhouse
You must spawn 2000 ragdolls.
Menu user
To get this achievement you need to open the spawn menu 100,000 times

War zone
You must kill 1000 hostile NPCs. I recommend spawning them in a closed space and throwing a grenade.
Bad friend
This time it's the same thing, but with regular NPCs. Only now it will be easier, since they can't harm you.
Innocent bystander
Now you need to kill 1000 animals. For example, crows. Good luck.
Popper
You need to spawn and pop 1000 balloons using the tool gun

Half marathon
You must play on one server for 4 hours
Marathon
You must play on one server for 8 hours
One day
Play 24 hours
One week
Play 168 hours
One month
Play 730
Addict
Play 8766 hours 0-0

10 thumbs
Get 10 likes on addons in steam.
100 thumbs
Get 100 likes on addons in steam.
1000 thumbs
Get 1000 likes on addons in steam.
Mega upload
Get 1000 likes on addon in steam.

Map loader
Download and open 20 maps installed via steam workshop
Secret phrase
Write in the chat of the game bloxwich
Friendly
Play with 10 friends
Startup millennium
Start Garry's mod 1000 times

Yes, I'm the real Garry!
To get this achievement, you need to go to the server where Harry plays. It would be difficult if he visited Garry's mod servers at all, but he stopped playing his own game altogether. So getting this achievement is not possible. But you can get it using, for example, Steam achievement manager. This program hacks achievements in games.