Infinite Ammo

Concept:

The concept of infinite ammo is to not worry about ammunition, mainly due to gameplay reasons.

Representation

Infinite ammo represents the ultimate offensive stance one can take since the player doesn’t have to worry about ammo conservation or tactics; but would rather just use the best gun in their possession and mow down the opposition.

This would not be the case for some side scrolling shooters since your default weapon is so weak, the game gives you infinite ammo as a sign to pick up better weapons.  

For game play reasons

The main reason why any game would give you infinite ammo is because the weapon equipped is much too weak compared to other weapons in the game. Because of this reason, it would make the game impossibly hard to limit your ammunition. While some games just place a very high number in lieu of infinite ammo; having the infinite sign (where the ammo counter would be), is a sign for the player not to worry about ammunition as well.

Another reason besides weak weaponry is the climatic point in the game where the enemies and game itself gets exponentially hard, and for game play reasons, will give you infinite ammo as well. This is primarily used in final boss battles after all the stages of the boss have been defeated. The infinite ammo on the biggest weaponry in the game is pure fan service since most people consider the game to be over at that time. This is, of course, due to the decrease in level of difficulty when infinite ammo is acquired.

Use as cheat

Infinite ammo is primarily used as a cheat in FPS games where there is never a guarantee that the default weapon has infinite ammo. This is of course in contrast to the Side scrolling shooter games (or similar genre), where the default weapon usually has infinite ammo. The reason why infinite ammo is the most frequent associated cheat is any games using guns, is simply because it takes away the need for ammo conservation, and players can just be “trigger happy”.

While widely accepted in single player games, the infinite ammo cheat is frowned upon in any multiplayer game that is taken seriously due to a dramatic “dumbing” down of gameplay.