Age ratings came about to prevent child harm to what they could potentially cause, so in 1994 the ESRB (European systemic risk board) started rating games with age rating which the congress approved of.
Age ratings were placed on the back of the game box where brief signs were labelled there with ratings of warnings for violence, smoking and other things.
The UK and the US have similar yet different age ratings, for example the UK
have an age rating labelled 3 for Universal, whereas the US have one labelled E for Everyone .
The rating for older children is 7 in the UK meaning that the age for these games are for children aged 7-11 which is the completely different in the US , the US has the rating E10+ which is for children 10 and older.
The next age rating is for teens where in the UK the rating is 12 for children between the ages of 12-15 whereas in the US it is just labelled as for Teens
After this the next rating in the UK is 16 which is just for teenagers aged between 16-17, whereas the counterpart in the US is rated for Mature with 17+.
Lastly the finale rating in the UK is 18 for people aged 18 and over can play any game no matter the rating as no explicit warnings apply to them as they're mature enough, in the US however the finale rating is Adults Only 18+ for anyone over 18 is mature enough.
The Universal rating PEGI 3 in the UK has its rating as it allows people of all ages to play the game as it has no restrictions guided towards it to stop that. However in the US the equivalent rating to PEGI 3 is E for everyone although the age rating doesn't mean everyone and is instead 6 and over as it includes any mild violence or language, containing minimal cartoon and fantasy.
The next rating is labelled PEGI 7 in the UK, meaning it can be frightening for younger children with very mild forms of violence being implied, non-detailed or non-realistic being acceptable. However in the US the equivalent rated PEGI 7 is E10+ for everyone over the age of 10 as it contains more cartoon, fantasy or mild violence, or minimal suggestive themes.
In the middle of all age rating is known as PEGI 12 in the UK, meaning people need to be at least 12 to play it on their own decision as it can include teachings of gambling, violence, drugs, bad language, sex and fear. However in the US the equivalent of PEGI 12 is rated Teen for ages of 13 and up as it contains violence, suggested themes, cycle humour, minimal blood, stimulated gambling and frequent use of language.
The rating after that in the UK is PEGI 16, so people aged 16 and above can play as it includes more mature and realistic violence against human characters such as gore and bloody scenes and everything in PEGI 12. However in the US the equivalent of PEGI 16 is Mature 17+ as it contains violence, suggested themes, crude humour, blood, gambling and language.
The last rating in the UK is PEGI 18, meaning people above the age of 18 can play because it includes things not suited for younger eyes and ears such as gross violence classed as horrific methods of bringing death or severe injury, including torture, decapitation and dismemberment, or its the other huge factor of nudity or sexual intercourse or just general sexual activity in the games background can make it classed as 18+. However in the US the equivalent of PEGI 18 is classed as Adults only 18+ meaning the same thing in terms of age as the UK as well as the same causes to make the age cap because of images of extreme gore or any sexual intercourse being done in the game or in the area that the game is played in.
Age ratings in games can be moved up into a more needed mature level of age to even play the game for small reasons and big reasons instructed by protection services like PEGI, for example the game Portal 2 was deemed offensive making the game aged for people 10 and above because of a small joke a character said mentioning orphans. Another game with the case of its age rating changing because of a controversy is Counter-Strike Global Offense (CSGO) mainly because of third party betting through the use of skin-gambling where players sell in game cosmetics for real life money leading to people having gambling addictions.