You're referring to the game "Bullet Force" from 2015!
: Utilize the game's fluid movement to stay mobile, making it harder for opponents to track you in high-traffic maps. : Experiment with different weapon classes—such as the Thompson SMG bullet force 2015
The immediate shock of Bullet Force in 2015 was technical. At the time, the Unity Web Player was dying due to security risks, and Flash was on its last legs. Bullet Force utilized the new Unity 5 engine and WebGL, meaning it required no plugins—just a modern browser. You're referring to the game "Bullet Force" from 2015