The very first NHL outdoor game was The Heritage Classic back in 2003. The Montreal Canadiens visited Edmonton where even the Oilers were prepared to play in -18C temperatures. But more than 57,000 fans were, spending all afternoon in the stands of Commonwealth Stadium to watch the game and the alumni game before that.
The toque-wearing Theodore has become the endearing image of the outdoor game.
The only challenger would be from the alumni game where, in a real throw back to the old days, the players cleaned the ice with shovels instead of a Zamboni. Guy Lafleur was captured most famously in this photo: