"Game improvement" irons consist of the largest category of iron sets on the market and encompasses a wide range of manufacturers and configurations. These irons will typically be "mid-sized" with a more traditional appeal. Game improvement-level irons are generally of neutral-bias. These types of irons are for those that can control his/her ball flight with greater consistency of the novice-level player.
"Super game improvement irons" or "entry-level" irons are targeted towards players of limited ability that need more help shaping their shots. Typically, super game improvement irons are draw-biased.
Game improvement irons are defined by a few features; usually there is a cavity in the back of the club head, which reduces the amount of twist and vibrate on the club when the ball misses the "sweet spot". It creates an effective hitting area and reduces the impacts of an off-center hit. There is a lower center of gravity in game improvement irons, because additional weight has been placed near the bottom of the club head. This causes the ball to send off at a higher angle, giving it more height and a softer landing. These particular irons are also made by pouring molten metal into a pre-formed cast, unlike regular irons that are made with forged blocks of steel.
Other common differences between game improvement irons and regular ones include a larger overall club head for more surface area and greater momentum, a thicker top line to help frame the ball, and club offset to give the golfer a split-second more to square the face at impact. Here are some examples of game improvement irons: