A trading card game based on Metal Gear Solid 2: Sons of Liberty was planned to be released, and went as far as the prototype stage, but was ultimately cancelled for undisclosed reasons. The prototype card designs were later included in The Document of Metal Gear Solid 2 among some photos relating to the games' development. Despite being cancelled, however, some of its mechanics, namely the COST and RANGE grid mechanics, were later reused for the games Metal Gear Acid and Metal Gear Acid 2.[1]