Flares are seen in the campaign several times. In the mission "The Crossroads", a flare is used to provide light in a darkened, collapsed building. In "The Mace", green flares are used to signal the approach of the advancing Canadian Army. Finally, in "Chambois", flares are used to mark targets for airstrikes.
In the level "Operation 40", a flare is shot to give when Woods, Mason, and Bowman to zipline into the facility. In "Crash Site", the Viet Cong throw flares at the player after they get off the boat. In addition, some are seen in garbage cans near the beginning of the level.
In campaign, the flares are briefly seen in the level "Struck Down", where Keegan picks one up when they are looking for Ajax, and holds it in the "Harries Technique" under his MP-443 Grach. Hesh is later on seen carrying one after Ajax dies.
The Flare also appears as a throwable equipment in Extinction. It will attract the Cryptids (except Rhinos), causing them to gather around it, become distracted and not attack the players or the Laser Drill (most of the time). They also try to touch it and also growl at it but no sound will be made. The flare lasts 20 seconds. Friendly cryptids are also affected by the flare. The flare is most useful for accuracy challenges, as the Cryptids will be relatively still and easy to shoot.