Hawk F-123 is a side-scrolling shoot-em-up. There is no background story in the game and no cutscenes; the player pilots a fighter plane, flying over various areas such as a desert, a sea, a city at night, etc. Most of the enemies are different types of aircraft, though a few stationary turrets appear as well.

The player-controlled fighter can pick up power-ups that change his primary weapon: red for a vulcan gun, yellow for energy bolts, and blue for laser. Each of these will increase in power (e.g. three lasers instead of one for the blue weapon) when the player repeatedly collects power-ups of the same color. Other power-ups add a secondary weapon or enhancement to any of the described above, such as homing missiles, fireballs, a wingman, etc. Secondary weapons are fired simultaneously with the main ones. In addition, special weapons can be collected and accumulated. These weapons are triggered by pressing a separate button, and include delayed bombs, exploding bullets, protective shields, and others.