OG stands for “Original Gangster”. The term “Original Gangster” was first coined during the gangster rap era. At that time “OG” was used to describe people who were one of the earliest gangsters. In other words, gangsters that were a part of the gang world for a long time were considered OG or original gangsters.
One might ask, what does gangster rap, and gangsters have to do with gaming. An OG is a person that has been a part of a gang for a long time. This means that an OG will have tons of experience on how things work and has tons of respect from other gangsters. In the same way, in gaming, an OG is a person that has been a part of a video game for a long time. Usually, OG is referred to a gamer who has been playing the game since its release. Just how Original Gangsters know how things run in a gang, OG gamers know all the top tricks of the game. For example, Aleksib is an OG CSGO player.
OG is not a term only given to players. Common terms that are used in a combination with OG include, OG tactic, OG Meta, OG Smoke, OG move, or OG build. All these terms relate to stuff that an OG gamer might do. If you too need to be considered as an OG, you need to play the game for a long time and be good at it.