The Chiefs and Bills broke football on Sunday

Bills-Chiefs was supposed to be a clash of the league's most assertive young quarterbacks, with Josh Allen and Patrick Mahomes representing the best of the sport's present and future. It lived up to that billing - even before both teams combined for three lead changes and a tie and scored 25 points in the final two minutes of regulation - only to have the outcome essentially determined by a coin flip.

That seesaw finish, in which life imitated a video game, just happened to be when Allen and Mahomes broke the sport.

In the contest's first 58 minutes, Allen barreled for 10 yards on a fourth-and-2. Mahomes scrambled for 49 yards on three carries on the ensuing possession, including an 8-yard touchdown run he capped by diving into the pylon.

He also did this two possessions later:

And that, to go up 14-7:

Allen answered by going 5-for-5 for 55 yards, including an 18-yard touchdown pass to Gabriel Davis. Allen also rushed twice for 20 yards on that drive, which lasted just 1:15 and evened the score 14-14. It still wasn't halftime.

The Chiefs broke the halftime tie with a field goal and expanded the lead to 23-14 with 2:06 left in the third quarter. But on the next play from scrimmage, Allen did this:

Tyreek Hill returned a punt 45 yards before being tackled by Bills punter Matt Haack. "One of the pivotal moments in this game," CBS play-by-play announcer Jim Nantz said, "has just taken place." Little did he know.

The Bills forced the Chiefs to kick a field goal in the fourth quarter after cornerback Dane Jackson blew up a trick play. There was still 8:58 remaining, with KC ahead 26-21. The game would have been thrilling enough had it ended then and there. But the real action hadn't begun. Neither offense would be stopped again.

The Bills used 17 plays and 7:01 of the clock to move 75 yards, with Allen at one point running right over Charvarius Ward and briefly knocking him out of the game. Allen also had to use all of his speed and athleticism to convert a fourth-and-4 in the most indescribable way imaginable …

… before finding Davis for a 27-yard touchdown pass four plays later on fourth-and-13. Allen made the Chiefs give chase again before connecting with Stefon Diggs for a two-point conversion in the back of the end zone. Buffalo led 29-26, but there was still 1:54 to play.

It took Kansas City just five plays and 52 seconds to respond, with Hill catching a crosser 14 yards downfield before splitting multiple defenders to sail 50 yards the rest of the way. Kansas City 33, Buffalo 29, 1:02 to go.

This is what happened next:

The Bills were going to win. Except Taylor Bass kicked off into the end zone to force a touchback, which meant the clock never started. The Chiefs, who still had all three timeouts, got the ball on their own 25 with 13 seconds left. It wound up being just enough time for Mahomes to even the score.

Buffalo set up its defense like this ...

... and Mahomes flipped a short pass to Hill, who raced for 19 yards. Timeout. Eight seconds left. With the Bills again defending to prevent a touchdown, rather than anything underneath, Mahomes zipped a toss to Kelce up the left seam for a 25-yard gain. Timeout. Three seconds left. Harrison Butker came on for a 49-yard field goal. Good. Overtime.

Allen called tails during the OT coin flip. It wound up being his biggest mistake of the night. What happened from there was more or less anticlimactic. The Chiefs waltzed 75 yards on eight plays, with Mahomes completing all six of his passes and capping it with a back-shoulder toss to Kelce for an 8-yard score.

Allen, who twice gave the Bills the lead in the final two minutes, including with 13 seconds to go, somehow lost this game. Through no fault of his own, he never again took the field.

There have been mind-boggling playoff games before, from the Chargers' 41-38 overtime victory over the Dolphins in the 1981 playoffs to the Bills' 35-point second-half comeback against the Oilers in the 1992 playoffs. The Colts came back from 21-6 down to beat the Patriots in the 2006 AFC title game, but even with Tom Brady and Peyton Manning at the height of their powers, those teams traded three field goals in the fourth quarter before Indy won it with a late TD. There are countless others.

The last decade alone featured the Seahawks coming back from trailing 19-7 to beat the Packers in overtime in the 2014 NFC title game; Malcolm Butler's Super Bowl interception; the Patriots erasing a 28-3 deficit against the Falcons in Super Bowl LI; the Minneapolis Miracle; Brady throwing for 501 yards in Super Bowl LII and losing to Nick Foles; and Patriots-Chiefs going to overtime in the 2018 AFC title matchup. Heck, the other three contests this weekend came down to the final play. But nothing matches this one in terms of the amount of concentrated action that went both ways with the game on the line.

The Bills and Chiefs are smart organizations with forward-thinking head coaches who embrace all the modern advances the sport offers, from analytics to an emphasis on efficiencies and the primacy of the passing game. Allen and Mahomes are the perfect exponents of the wisdom of this approach. They're also unicorns.

Allen and Mahomes played a perfect game Sunday night that tore through the confines of what's imaginable. An incomparable duel punctuated with great situational awareness was stopped only by the cruel limitations of the NFL's overtime rules. Mahomes plays on; Allen must wait until next year. What might they do next?

Dom Cosentino is a senior features writer at theScore.