The logo.
The Entertainment Software Rating Board, or ESRB, is a company that rates video games based on their content, and determines what age groups the game is appropriate for. This system is used in the United States and Canada. Shattered and Shattered 2 have been rated M for Mature by this system.
Summary
The ESRB is a self-regulatory organization that assigns age and content ratings, enforces industry-adopted advertising guidelines, and ensures responsible online privacy principles for computer and video games in the United States, nearly all of Canada, and Mexico. The ESRB was established in 1994 by the Entertainment Software Association (formerly the Interactive Digital Software Association), in response to criticism of violent content found in video games such as Night Trap, Mortal Kombat, and other controversial video games portraying excessively violent or intense sexual situations.
Relations to Shattered
Originally rated T for teen, the rating was changed for Shattered when curse words were found around the game, used as dialogue. Chris6dProductions admits they knew they were going to get the M rating by adding this, but did it to enhance realism in the game. Shattered 2 was rated M as well.