The Rocks were to first be seen being used in the earliest version of rooftops10 where after gas mask citizens throw beer bottles at these wooded windows and their attempts fail they throw a rock at the wooded window braking it before being chased and getting killed by two Wasteland Scanners. In updated revisions these gas mask citizens turn into normal Citizens using MP5K's to try and kill the scanners but with a rock laying by one of them where Gordon Freeman would obtain it. Originally the player was to obtain the rock through the Canals and Skyscraper maps though doesn't appear in the maps. The rock has three versions with different edges and can be used by both citizens and Gordon.
- The cut HUD for the Rocks shows a hand throwing a rock. The HUD is called " Thrown ". When a rock is picked up the HUD will display the hand throwing the rock image.