The ability to tell friend from foe is one of the most fundamental differentiators in all video games. Some games use naming, visual bars, symbols or color markers. For those who have trouble differentiating between similar colors, small markings can help gamers tell the difference between friend, enemy, or really difficult enemy.
In Guild Wars 2, enemies are marked by red bars with numbers representing mob level and accompanying symbols to declare the level of the faculty in either a gold or silver star.
In Battlefield 3, an option can be enabled to place small blue ‘Doritos’ over the heads of allies. This allows gamers to quickly recognize that those without the marking are enemies.
A teen has trouble seeing enemies on certain backgrounds of a game with a variety of maps. Without the ability to change the colors of the enemies or mark them in some way, he will be caught unaware when an enemy walks on-screen.