Chris Heisey receives a congratulatory bath after hitting the game-winning homer for Washington. (Greg Fiume/Getty Images)

Describing what happened Sunday at Nationals Park is a nearly impossible task. The longest regular season game in Washington Nationals history had the following: a solid Stephen Strasburg start doomed by a three-run home run; a Bryce Harper game-tying, pinch-hit home run in the ninth inning; starter Joe Ross pinch-hitting in the 10th inning; Nationals players wearing hats inside out and upside down in the dugout in the 14th inning; and reliever Yusmeiro Petit giving up the go-ahead run in the 15th inning on his 77th pitch of the day — only to be bailed out by reliever Oliver Perez’s improbable game-tying perfect drag bunt in the bottom of the frame.

That enough?

The zaniness finally ended in the 16th inning, after 5 hours 56 minutes, when Chris Heisey smashed his first walkoff home run in the Nationals’ 6-5 win over the Minnesota Twins. Thirty-eight players, including 14 pitchers, appeared in the game. The teams combined for 516 pitches, 27 hits and 32 strikeouts.

“I feel like I just came out of the twilight zone,” Nationals Manager Dusty Baker said. “Man, that was some game. That was a roller coaster game of emotions.”

The Nationals had many chances to avoid this situation. They stranded 14 runners, many in the early innings, a combination of the Twins’ good defense, notably in the outfield, and the Nationals’ missed swings.

“I love these guys because they don’t give up,” Baker said. “They seem unfazed by it. Act like they knew we were going to win, and they did. That’s the power of belief.”

Sunday’s game had everything a game could offer, from dramatic highs to head-shaking oddities. Bench coach Chris Speier, first base coach Davey Lopes and Baker, in his 21st season as a manager, have seen thousands of games combined, and the three agreed this was the wildest game they had been a part of.

“We always say: ‘Go to the ballpark; you always see something you’ve never seen before,’ ” Baker said. “Well, I certainly hadn’t seen anything like this.”

The Nationals leaned heavily on Strasburg and Petit because the bullpen was two relievers short Sunday, with Baker wanting to avoid using Blake Treinen and Shawn Kelley because of heavy recent workloads. So he stuck with Strasburg in the eighth inning — even with two men on and one out — against Brian Dozier. Baker hoped Strasburg could finish the inning, but the power-hitting second baseman smashed a three-run home run on Strasburg’s 114th pitch, giving the Twins a 4-1 lead.

“Wish I could take one pitch back, but it’s a learning process,” Strasburg said. “It’s not going to be the last one, but I’m just happy with the way the guys fought and picked me up.”

The Nationals nearly regained the tie as quickly as they had lost it. With Anthony Rendon on base, Jayson Werth drilled a ball that fell three feet short of landing over the fence and had to settle for a double. Wilson Ramos brought them in with a double that trimmed the Nationals’ deficit to 4-3. Washington couldn’t, however, bring the tying run home, a theme of squandered opportunities that lingered all game for both teams.

Harper saved the Nationals with a brief appearance that Baker foretold before the game. He wanted to give Harper a day off and only use him as a pinch hitter. When Baker managed Barry Bonds with the San Francisco Giants, he one time had to double-switch the slugger into a game on an off-day; the game went 18 innings.

“I didn’t want to put Harp out there and be tempted to go against my word,” Baker said. “I told him that before the game started: ‘Wait for a time so the fans can go crazy and you can be the hero, and then I’ll take you out.’ I’m not always right, but I was right today.”

Harper provided the dramatic moment that allowed the game to continue. Facing Twins closer Kevin Jepsen, Harper fouled off three pitches and held off on a ball just off the plate. He then crushed a low, full-count fastball to straightaway center field for a home run, his ninth of the season. The stadium and his teammates erupted, and Harper bear-hugged Baker in the dugout. Heisey took right field the next inning.

“It all worked out,” Harper said. “Heisey came in and hit the homer. [Baker] pulled everything he could out of his hat, and it worked for him. It was awesome to see.”

The teams dragged on for seven more innings. Baker was out of bench options, so he took out closer Jonathan Papelbon and turned to his most athletic pitcher, Ross, who singled. But Jose Lobaton grounded into an inning-ending double play. Baker then turned to Petit, who had thrown 43 pitches four days before. Petit provided a needed boost to a shorthanded bullpen with four scoreless innings before the Twins finally got to him in his fifth. With two outs in the 15th, Petit gave up the go-ahead RBI single to Miguel Sano.

“Petit did his job,” Perez said. “I was going to pitch the most I could, too.”

But Perez saved the Nationals with his smarts at the plate in his first at-bat since 2010. After Danny Espinosa walked with two outs, Perez was due up but thought he would be replaced by a pinch hitter — except no bench players were left. Twins Manager Paul Molitor called for a reliever, right-hander Michael Tonkin, to face Perez.

Perez saw third baseman Eduardo Nunez playing back, so he dropped down a bunt in his direction. Catcher John Ryan Murphy picked up the ball instead of letting it go foul. His throw was wide of first base, and Espinosa scored to tie the game. The Nationals’ dugout went wild.

An inning later, Heisey ended it with a home run to left.

“All-around team effort,” Heisey said. “You can’t really get more team than we did today.”