Global Offensive, like prior games in the Counter-Strike series, is an objective-based, multiplayer first-person shooter. Two opposing teams, the Terrorists and the Counter-Terrorists compete in game modes to repeatedly complete objectives, such as securing a location to plant or defuse a bomb and rescuing or capturing hostages. At the end of each short round, players are rewarded based on individual and team performance with in-game currency to spend on other weapons or utility in subsequent rounds. Winning rounds generally rewards more money than losing does, and completing map-based objectives, including killing enemies, gives additional cash bonuses.
Global Offensive has eight official game modes: Competitive, Casual, Deathmatch, Arms Race, Demolition, Wingman, Flying Scotsman, and Danger Zone. Competitive mode, the primary gameplay experience, pits two teams of five players against each other in a best-of-30 match. When playing Competitive, players have a skill rank based on an Elo rating system and are paired with and against other players around the same ranking. The Casual and Deathmatch modes are less serious than Competitive mode and do not register friendly fire. Both are primarily used as a practice tool. Arms Race and Demolition, both based on mods for previous iterations in the series, were added alongside eight new maps for the modes. Arms Race is the Global Offensive variant of the "Gun Game" mode in other games in the series. Demolition is another bomb-defuse game mode, with gun upgrades only given to players who killed an enemy in the previous round. Wingman is a two-on-two bomb defuse game mode taking place over sixteen rounds. Similar to Competitive, players are paired based on a dynamic skill ranking.
There are five categories of purchasable weaponry: rifles, submachine guns, "heavy" weaponry (light machine guns and shotguns), pistols, and grenades. Each gun in Global Offensive has a unique recoil pattern that can be controlled, a gameplay feature the series has long been associated with. Global Offensive also introduced weapons and equipment not seen in previous installments, including tasers and an incendiary grenade.