There are six main variations of Unkitted American Football (American Football without the pads and helmets)-
American 7s is a 7-a-side unkitted tackle version of the sport, bringing the game back to its origins as a version of Rugby. The man who codified it in New Jersey in 2006 said he played American Football in High School, but college wasn’t an option so he continued playing pick-up games of American Football in parks where players have no protective helmets or pads. He decided there was a need for the game to be codified and organised leagues set up.
Flag Football is the earliest and is usually played with either 5 or 7 players on a team, with no contact allowed – a flag is attached to the players waist by a belt which is pulled off in order to tackle the ball-carrier. It is Coed.
Early Gridiron Football from 1850s to 1919 (i.e. Prior to the formation of the NFL) was a very rough sport with little in the form of rules governing it. Players also had very little protection beyond the minimum jersey, shorts, socks and boots.
Beach Football is a non-contact version of the sport played on beaches in America.
Wheelchair American Football is as the name suggests American Football played in Wheelchairs.
Robot Football is played with remote-controlled Robot Cars.
The idea for American 7s came to Ryan DePaul late in 2002. His High School Football playing career was over and there was no possibility of playing College Football. He was playing pick-up, no pads or helmet football in parks and thought it needed codifying, so in 2005 he began to develop 7v7 No Pads, No Helmet, Tackle American Football.
In 2014 he was approached by lifelong friend and entrepreneur, Sener Korkusuz about launching the League to Major League level. Soon afterwards the American 7s Football League was born, starting its first season in March 2015. [Ref: 1]
American 7s Football League
American 7s Football League (Overview):
Pixture Credit:  A7FL Facebook (2020) Photo, August 22, 2020 [Internet] Available from: https://i0.wp.com/www.a7fl.com/wp-content/uploads/2020/07/A7FLBackInMotionFINAL.png?resize=294%2C300&ssl=1 [Accessed 12 September 2020]
References:  A7FL (2020) About [Internet] Available from: https://www.a7fl.com/about-a7fl/ [Accessed 23 May 2020]
Flag Football World
Flag Football was invented in the 1940s as a non-contact version of American Football.
The first Pro leagues were set up in the coming decades, with a America-wide League currently in operation with Regional Playoffs followed by a Final with a purse of $1 Million, which includes teams of former NFL players.
Below you will find links to Top-Level Leagues Worldwide and International Tournaments:
Flag Oceane Logo reference:  Flag Oceane Wayback Machine (2004) ball [Internet] Available from: http://web.archive.org/web/20070824020039im_/http://www.flag-oceane.com/images/ball.gif [Accessed 20 August 2021]
NFL Flag Football
The National Football League runs an Underage Flag Football Tournament with Qualifiers all over the World as well as Nationally in the USA for Children and Teenagers aged 6U to 17U, both Boys and Girls.
World Flag Tournaments held in Europe.
A Number of Big Flag Football Tournaments in Europe have attracted teams from all over the World
Flag Oceane, held in Le Havre, Normandie, France was the biggest Flag Football tournament in Europe from 1999-2008.
Big Bowl, in Waldorf in Germany, took over as the Big European Flag Competition from 2008-2017.
Flagging New Year in Edinburgh, Scotland took over that mantle in 2018.
NFL and World Flag Football
NFL Schools Flag Championships; Big Bowl (Germany)
NFL Schools Flag Football Championships
NFL European Schools Flag Football Championships (seasons):
NFL Europe Schools Flag Football Championships Finland Qualifying Championship (seasons):
World Flag Football Tournaments
World Flag Football (Seasons):
Flagging New Year (Scotland / Europe / World):
Big Bowl (Germany / Europe / World):
Flag Oceane (France / Europe / World):
Picture Credit:  NFL Flag Football Wayback Machine (2002) flag [Internet] Available from: http://web.archive.org/web/20030726154329im_/https://www.play-football.net/images/logos/flag.gif [Accessed 2 March 2021]
Early Gridiron Football (1850s-1919)
Gridiron is another name for American Football because in its early days the field was marked out in a grid pattern.
The first Pro american Football League was the Western Pennsylvania Pro Football Circuit in the Pittsburgh and surrounding Coal-Mining areas. The Leagues were unofficial, and the players paid under the counter. The first Word series was held in 1901, actually a five-team tournament, and that lasted two seasons. In 1903 the Ohio League became the first League to Officially pay players and when that League saw players salaries spiral due to competition from other teams for their services, four Ohio League teams joined forces with teams from Pennsylvania and Upstate New York to form the American Professional Football Association in 1920, which in 1922 changed its name to the National Football League, the Major League we know today. Canton is home to the Pro Football Hall of Fame, and the NFL Preseason opens there with the latest induction of Hall of Fame players in honour of the Canton Bulldogs, prime players in the Ohio League and formation of the NFL.
World Series of Pro Football; Pennsylvania League; Ohio League
World Series of Pro Football
National Football League (Seasons): 1902
Picture Credit: 1920s football action. Thousands of spectators watch from double decker stadium seats. By Everett Collection[Shutterstock]