"S.T.A.L.K.E.R." uses "realistic" bullet physics, that is, the way that the bullets move is like how a bullet would move in real life. The bullet physics are similar to tactical shooters such as "Ghost Recon Advanced Warfighter" or "Call of Duty 2". Bullets are affected by gravity, and weapons are highly inaccurate when fired "from the hip". To be sure of hitting the enemy at long range, players must aim using the iron sights on their guns. Also, bullets do "realistic" damage, and the player can die after only being shot a few times (but to make up for this, later in the game the player can get different armor suits that increase the amount the player can be shot before dying).