Those Steam Sale things seem to work pretty well, then. Garry's Mod has enjoyed quite a bit of renewed interest over Steam's Winter Sale, sitting on the front page and selling for £1.74, pushing it over 10 million units sold.
The Steam Sale ends on January 4th, so why not look through our list of the best PC games and see if you can buy them all while they're cheap.
Garry Newman revealed the latest milestone over Twitter:
Jesus christ. GMod sold its ten millionth copy over new years.— Garry Newman (@garrynewman) January 2, 2016
This means Garry's Mod has sold almost 4 million units since September 2014.
It took Garry's Mod 8 years to hit the 6 million mark, with the following 4 million sales coming in just over a year - perhaps pointing to its sale price being the sweet spot for people to take a punt on the bizarre Source Engine sandbox.
The game has seen a constant stream of updates since its 2006 release, with a new one imminent. This support is likely part of the reason the game has enjoyed such a long life.
It should keep people happy until Garry's Mod 2, at least.
Do you play Garry's Mod? Let us know what you you like to do in the comments.