Outdoor hockey changes the inputs. Ice made in a stadium bowl is softer and more variable than an arena sheet, the puck bounces more, and passing tends to be shorter and simpler, which is why totals and puck line markets behave differently from an ordinary meeting. Weather, glare and wind can favour one end for a whole period, and breaks can be extended for ice repair, which interrupts the rhythm of the team carrying play. Goaltenders deal with unfamiliar sightlines, so save percentages drift from normal expectations.
This game is the NHL Winter Classic, the league's showcase outdoor fixture, here between the Colorado Avalanche and the Utah Mammoth. It is a single regular season meeting under normal rules, with overtime and a shootout if the teams are level, and the points count like any other.
A stadium game also runs to a different schedule. The build up is long, warm ups are cut short, and the teams change ends partway through the third period so neither side defends the same net in the conditions for the whole of the closing stretch. Passing that would be routine indoors is chipped off the boards instead, shifts run shorter, and communication suffers because the crowd sits far back from the glass. Newcomers should use the opening period as the read on how the surface is actually playing.