Alex Vreeke is a video game-loving, musician student and resident of Brantford, New Hampshire. In the 2017 film, Mason Guccione plays the teenager Alex (who is credited as "Gamer"), while an uncredited Colin Hanks portrays the adult Alex after he returns to 1996 and appears 20 years later. Alex later returns in the 2019 film to help Bethany get back into "JUMANJI" and rescue their friends with Alex willingly joining the mission as Seaplane McDonough once more.
In 1996, Mr. Vreeke was jogging on the beach and stopped to pick up the "JUMANJI" board game after hearing the sounds of drums, and decided to take it home to his son, thinking he would like it. But when Alex examined the game, he immediately lost interest in it, asking himself, "Who plays board games?" in a snarky tone. "JUMANJI", sensing Alex's interest in video games, adapted to modern times and tastes by magically transforming its game-board into a video game cartridge which caught Alex's attention later that night. As he played it, he selected the avatar Seaplane McDonough and was subsequently teleported into the game. Like Alan Parrish before him, the sudden and prolonged uncertainty of Alex's fate led to his parents, and more notably, his father losing his faith and the house being dilapidated for years.
Alone in "JUMANJI", Seaplane (Alex) had attempted to reach the Jaguar Shrine by using both a hot air balloon and a plane to escape from the game. Both escape attempts were unsuccessful after crashing the hot air balloon and his plane being shot down by Orangutans: costing Seaplane (Alex) two lives and leaving him with enough severe anxiety to make him stay clear of the Shed.
Twenty-one years later in 2017, four students in Brantford High School: Spencer Gilpin, Anthony "Fridge" Johnson, Bethany Walker, and Martha Kaply, (who previously found "JUMANJI" when they were placed in detention together) each became transported into the game too. Along the way, the group started working together to obtain a clue from a Black Mamba at "The Bazaar", but were cornered by Professor Van Pelt's Army, yet fortunately rescued by Jefferson "Seaplane" McDonough (Alex) with a distraction using a smoke bomb. Recuperating in a treehouse built by Alan Parrish, Seaplane (Alex) informed the newcomers about the house and explained to them that many other players were sent into the game, even before him. Seaplane (Alex) laid the treehouse with citronella candles to keep himself safe from Mosquitoes, as their bites are his weakness. By adding the missing avatar and player: Seaplane McDonough, the group quickly realize they were actually meant to find him. Despite Seaplane (Alex) being terrified of going back to the "Transportation Shed" due to being on his last life, he agreed to venture the rest of the way with them back home.
On the way, Seaplane (Alex) used some outdated slang and interest in old celebrities, raising questions on the year he thinks it is: Alex, thinking he has only been in the game for a few months, is regrettably corrected by the three male avatars that it's not 1996 at all, he has actually been in the game for twenty-one years. Distraught, Seaplane (Alex) became silent with shock before the group vowed to help him return home. Working together, the group broke into the "Transportation Shed", which brought Seaplane (Alex) into a state of panic as he had previously gone through traumatic experiences in the shed. After the gang helped Alex to calm down from his panicked state, they commandeer the Evac-Helicopter to cross the canyon, but lost control because of taking gunfire from Van Pelt's soldiers and flying into "The Canyon". After issues with the helicopter, the group landed safely on the other side of the canyon. Almost immediately, Seaplane (Alex) applauded his new friends for helping do something he couldn't do before but quickly began to lose his last life after a Mosquito bit him. Shelly Oberon (Bethany) performed CPR and mouth-to-mouth in time and saved Seaplane (Alex) by transferring a spare life to him.
Finally reaching "The Defenders", Franklin "Mouse" Finbar (Fridge) conducted a plan akin to football to survive the level, which included Seaplane (Alex) acting as a distraction to the Jaguars so Smolder Bravestone (Spencer) could use the main path to make it to the Jaguar Statue. When the five players reached the base of the Jaguar Statue, they found Professor Van Pelt holding Shelly Oberon (Bethany) as a hostage. Because Alex and Bethany have bonded over the course of the game and kindled a subtle romance, Seaplane (Alex) tried to protect Shelly (Bethany) from Van Pelt's gunfire as Ruby Roundhouse (Martha) and Smolder Bravestone (Spencer) teamed up to restore the Jewel to the Jaguar's Eye.
The game successfully ended with all the players all calling out the game’s name, with Van Pelt disintegrating into creatures he previously controlled. Nigel Billingsley then appeared and offered Alex shake his hand first, allowing him to return to reality in Brantford as the other players did the same, and revert to their former selves. When the high-schoolers were put back in 2017, they noticed Alex did not come back with them, worrying that "JUMANJI" might have kept him. Curious and looking for Alex, they passed by the Vreeke household (once the neglected home of Alex's father "Old Man" Vreeke), and discover it has been restored.
When a now adult Alex appeared, he recognized the group and expressed joy to meet them again, thanking them for helping him and told them he was returned to the moment he started the game in 1996, and history was changed. He is now married and had a son named Andy while his eldest daughter was named after Bethany, out of gratitude for Bethany saving his life.
After Spencer returns to "JUMANJI", the rest of the team goes in to save him, along with, inadvertently Eddie Gilpin and Milo Walker. However, Bethany gets stranded outside and can't restart the game. Needing help, Bethany visits Alex at his home where she meets her namesake. Bethany convinces Alex, who is concerned about the potential danger, to help her. Together they manage to restart "JUMANJI" and Alex chooses to join Bethany in traveling into the game world once more to rescue their friends.
Alex returns to "JUMANJI" in the body of his old avatar Seaplane McDonough while Bethany gains the new avatar of the Pegasus Cyclone. Using his experience in "JUMANJI", Alex buys the group warmer clothes after he realizes how far north they've gone. Alex and Bethany ultimately arrive just in time to rescue the others from Mandrils and are surprised and amused by the group having mixed-up avatars. When the group found a river that could switch around their avatars, Alex remained on dry land with Martha since they had the correct avatars, but Eddie and Milo were kidnapped that night by Jurgen the Brutal's soldiers. When the team expresses insecurities about their ability to succeed in their mission, Alex reminds them that they can do anything and he knows that better than anyone.
While Martha and Spencer climb the side of the mountain, Alex, Fridge and Bethany sneak up the main path. Alex realizes that in his outfit, he can blend in with Jurgen's soldiers and is annoyed when Fridge and Bethany ignore his orders to remain behind. However, they are mistaken for the men Jurgen is meeting with and let in. As the rest of the group tries to get the Falcon Jewel, Alex attempts to rescue Milo from a booby-trapped barn, losing two of his lives in the process. Alex finally managed to reach Milo and was amazed by what he saw when he accidentally activated Cyclone's menu of strengths and weaknesses.
As the rest of the group watched Spencer's struggle to reach Jurgen on a zeppelin, Alex returned aboard Milo who attempted to go after Spencer with Eddie. Aware that Cyclone had wings, Alex urged Eddie to listen to his friend. After Eddie retrieved the jewel from Spencer and showed it to the sun, it was Alex who realized that the group had to call out "JUMANJI" to finish the game. Alex was returned to Earth once again by Nigel and shared a smile with Bethany upon their return.
- Alex's role essentially serves as a parallel to that of Alan Parrish, down to going missing for 20+ years, his family's lives after the disappearance effects and time being reversed when the game is won, even finding a treehouse made by Parrish. Unlike with Judy and Peter Shepherd, Alex being returned to his own time does not undo the game played by the other teens or lose their memories, akin to the animated series versions, where the memories of their adventures are kept.
- While it's not explicitly told whether modern day Alex has a wife, a woman is seen in the passenger seat of their mini-van as he arrives back at his house before seeing the kids.