Here are 10 observations from the game:
1. Patrick Mahomes' day
It was the NFL debut for quarterback Patrick Mahomes, who became the first rookie to start for the Chiefs under center in more than 30 years, and he showed plenty of the gun-slinging and playmaking ability that people have seen from him since his days at Texas Tech.
On multiple occasions, Mahomes made throws on the run and made plays from outside the pocket—firing darts all over the field, including a late fourth-quarter missile to Demarcus Robinson for 12 yards that was a key play on a game-winning drive. It's a play you'll see a lot of replays of this week.
Mahomes was seemingly done for the day as he left in the fourth quarter and Tyler Bray got in for a couple of series, but the first play after Mahomes left resulted in a fumble that was returned for a touchdown by the Broncos.
Mahomes re-entered the game after the Broncos tied it on a fourth-down touchdown pass from Broncos' quarterback Paxton Lynch to Demaryius Thomas.
At that point, there was a little less than three minutes left in the game and it was tied, 24-24.
Mahomes was put back in for a chance at a game-winning drive, and he delivered. He went 4 of 5 for 52 yards on a final drive that led to Harrison Butker's 30-yard field goal as time expired, which gave the Chiefs the win.
Overall, Mahomes finished 22 of 35 for 284 yards and an interception.
And he was particularly good on third down, finishing 5 of 7 for 93 yards, and one of those incompletions was actually a drop in the end zone.
Quite the NFL debut for the rookie quarterback.
2. Kareem Hunt got the rushing title
It was a storyline coming into the game—that Chiefs' rookie running back Kareem Hunt had a shot at the NFL's rushing title. He would need just a few carries on Sunday.
And as it turned out, he only needed one.
Hunt trailed the Los Angeles Rams' Todd Gurley by just 13 yards coming into Sunday's game, and Gurley was already ruled out for this week as the Rams look towards the playoffs. The Steelers' Le'Veon Bell, who trailed Hunt by just one yard, wasn't going to play for the Steelers either for the same reason.
Therefore, Hunt needed just 14 yards to move into the top spot, and on second-and-10 from the Broncos' 35-yard line on the Chiefs' first offensive drive of the game, Hunt and took his first (and only) handoff of the game 35 yards right through the middle of the Broncos' defense to get the Chiefs into the end zone, and to also get himself a rushing title.
Fellow running back Charcandrick West, who would have had ample opportunities in this game, was sick all week and was declared out on Saturday before the team left for Colorado.
Hunt finishes the regular season with an NFL-best 1,327 yards rushing.
3. Chiefs' strike quickly to begin the game
The Chiefs' offense got things going early, marching 86 yards on their first drive on just five plays and capping it off with Hunt's 35-yard touchdown run.
The entire drive took just 57 seconds off the clock.
The key play was a beautiful thrown down the seam on third-and-10 from Mahomes to tight end Demetrius Harris, who had bracket coverage and wasn't touched as he came down to the ground after extending his arms to make a great catch over the middle. Harris jumped up and raced down the field to pick up additional yardage.
The Chiefs' second drive ended with a Mahomes' interception on a pass that sailed a little high across the middle.
4. Leon McQuay III flashed early, Tanoh Kpassagnon got his first career sack
With several veterans getting the day off, it was an opportunity for some young guys to make plays, and a few flashed their ability on Sunday.
Before he left the game for a brief period in the first quarter after being evaluated for a concussion, Chiefs' rookie safety Leon McQuay had a couple of nice tackles, including one in which he fought off a block from a Broncos' offensive lineman and was able to make the tackle that resulted in just a short gain.
McQuay, who was lined up in the box pre-snap on the play, got off the block and still tracked down Broncos' starting running back C.J. Anderson to make the tackle off the right edge. McQuay also had a nice pass breakup late in the game on Broncos' receiver Demaryius Thomas inside the red zone.
Then, late in the third quarter, rookie second-round pick Tanoh Kpassagnon fought off a block and stayed with the play long enough to get the first sack of his career. He would later add another sack as well.
5. Anthony Sherman had a career day
Late in the first half with less than two minutes remaining, Chiefs' fullback Anthony Sherman took a handoff on second-and-goal from the Broncos' 1-yard line and fought his way into the end zone for the touchdown.
It was the first rushing touchdown of Sherman's seven-year NFL career. The score also gave the Chiefs the lead back at 14-10.
Coming into the game, Sherman had carried the ball just six times for 14 yards in 107 career games. He finished Sunday's game with 14 carries for 40 yards and a touchdown, adding three receptions for 21 yards as well.
6. Terrance Smith got an interception, and Chris Jones' sack leads to a scoop and score
Late in the first half, Smith was in the right place at the right time as Lynch tried to fit one through a tight window across the middle.
After linebacker Ramik Wilson looked to have a beat on the ball, it was deflected into the hands of Smith, who took it seven yards the other way for the Chiefs' defense.
It was the first interception of Smith's career.
Then, midway through the third quarter, the Chiefs' defense made another big play.
Chris Jones—the Chiefs' standout second-year defensive lineman, knifed through the middle of the Broncos' offensive line and brought down Lynch for a sack on a second-and-9 play from the Broncos' 29-yard line. After the ball was loose on the field and kicked around a few times, Ramik Wilson eventually picked it up and raced 11 yards for the touchdown.
It was the Chiefs' 11th takeaway over the past four games, and Jones' third sack in his last four games. He now has 6.5 on the season.
Terrance Mitchell would later add another interception, which came inside the red zone as he intercepted Lynch at the Chiefs' two-yard line and returned it 40 yards the other way.
7. Albert Wilson had a big day
It was a benefit for Mahomes in his first career start to have a veteran presence like Albert Wilson on the outside.
And that translated to big numbers for Wilson as well. He finished with a career-high 10 catches for 147 yards.
8. Harrison Butker moves into Top 10 in NFL history
Late in the third quarter, Butker hit a 20-yard field goal that gave him 37 made field goals for the season, which put him tied for 9th in NFL history in that category. He already had the Chiefs' franchise record.
The NFL record was set by David Akers, who had 44 for San Francisco in 2011.
Then, Butker's 30-yard game-winner gave him 38 made field goals for the year, which moved him into a tie for fifth place on the NFL's all-time list.
Not a bad rookie season for Butker.
9. It was cold
The temperature at kickoff was 17 degrees, which tied it for the fifth-coldest game in Broncos' franchise history.
And it was still warmer than Kansas City was on Sunday, so there's that.
Photos from the Chiefs Week 17 matchup against the Broncos
10. Several Chiefs left the game with injuries
On the final play of the first quarter, Chiefs' receiver and returner De'Anthony Thomas fielded a punt over his shoulder and was tackled trying to get around the right edge.
After the play, Thomas remained down on the field and was surrounded by trainers and Chiefs' staff members. He was ultimately taken off the field on a cart and quickly ruled out for the game.
Running back Akeem Hunt also left with an ankle injury.
Cornerback Phillip Gaines left early with an elbow injury, and then defensive lineman Rakeem Nunez-Roches also left the game with an ankle injury.