Its fans can't live without it, travelling overseas to watch their charges or creating Wikipedia pages for fictional players.
But people who don't like it really don't like it.
https://twitter.com/callumhbcfc/status/630517293919961088
For the second window running, the BBC have enlisted the help of Football Manager expert Alex Stewart to help run the rule over unknown quantities on deadline day.
The reactions have been...mixed.
https://twitter.com/GoalscorerC/status/638675970497581056
https://twitter.com/AFHStewart/status/638672428550516736
https://twitter.com/AFHStewart/status/638676305714774017
