There have been lots of great freeware games,and I tell you the five best ones.

1. Mono



Mono is a fantastic simple game. Your objective is to change the color of the screen to the opposite color. The player starts with a white or black background and has to change it to black or white by shooting at colored balls that explode into halves and leave traces of their color on the background. You get extras like additional firepower which you need badly later in the game.