Variants of football have been codified for reduced-sized teams (i.e. five-a-side football) play in non-field environments (i.e. beach soccer, indoor soccer, and futsal) and for teams with disabilities (i.e. paralympic association football).
Bandy is a variant of hockey played on ice the size of a football pitch, under rules similar to those of association football. It is often called “the football of winter” and is played professionally in Russia and in Sweden.
One of the attractions of association football is that a casual game can be played with only minimal equipment – a basic game can be played on almost any open area of reasonable size with just a ball and items to mark the positions of two sets of goalposts. Such games can often have team sizes that vary considerably from 11-a-side, use a limited and/or modified subset of the official rules, and are likely to be self-officiated by the players.