Indoor American football, or arena football, is a variation of gridiron football played at ice hockey-sized indoor arenas. While varying in details from league to league, the rules of indoor football are designed to allow for play in a smaller arena. It is distinct from traditional American or Canadian football played in larger domed or open-air stadiums, although several early college football games contested on full-sized or nearly full-sized fields at Chicago Coliseum (1890s) and Atlantic City Convention Center (1930s and 1960s) helped to show that football could be played as an indoor game.