The usual fare that plays at Fantastic Fest is hilariously brutal, pushing audience members to the limits of what they can reasonably handle, which makes it all the more interesting that the relatively bloodless “I Declare War” won the Audience Award at last year’s festival. The film portrays children’s games in a truly fantastical, wildly entertaining story about the dynamics of childhood and friendship.

Over the course of a long, hot afternoon, two armies of adolescents play a game of war that takes on added relevance when filtered through their imaginations, which allows for massive machine guns, bazookas and even superpowers. Gen. PK (Gage Munroe) has never lost a war, and his best friend Kwon (Siam Yu) is happy to follow the leader. When an opposing teammate, Skinner (Michael Friend) strikes out and takes Kwon hostage to win the war, PK must choose between his best friend and his perfect record.

Without a single adult character to interact with, the child actors are forced to carry every moment of “I Declare War,” and directors Jason Lapeyre — who also wrote the script — and Robert Wilson have assembled a consistently strong ensemble of youthful thespians.

Munroe makes for a charismatic leader, full of bullheaded determination, but his PK is tragically flawed, and he plays every note gracefully. The
cartoonishly evil Skinner, on the other hand, fits cleanly into the box of the film’s antagonist. However, the finale reveals that his villainy comes from a real, wounded place, and Friend makes the revelations land painfully. Mackenzie Munro plays Jess, the only girl in the game, and she’s enormously charming and wily as her character navigates the boys-only terrain of war. Yu is more inconsistent, nailing the moments in which Kwon and PK are bonding, but struggling when he has to be intimidating or authoritative.

The direction from Wilson and Lapeyre is stylish, casting a lot of action film tropes in new and creative ways, and they handle the film’s quiet, emotional moments with the same intensity and sense of purpose that they bring to the bombastic, effective action scenes. The script from Lapeyre is involving and exciting, and he’s got a knack for crafting likable, spunky characters that feel like real kids. PK, Jess and Kwon all talk with the fumbling stupidity and undeveloped fervor of adolescents, and Lapeyre’s firm handle on the way kids behave allows the film to cast them as war-weary soldiers all the more effectively.

The film’s premise — letting kids with imaginary guns run amok — may inspire squirms, but the added stakes of the visuals and the smart tonal game the film plays make sure it roundly earns every mock-up assault rifle and hand grenade. While the war allows some of the players to delve into their worst impulses — on the rare occasions the cartoonish violence overlaps into reality — the film treats it with deft care, never letting things slip into ugliness.

“I Declare War” may be an entertaining action film, but more than that, it’s an observant, authentic, coming-of-age film, perfectly capturing the potential of imagination. The compelling characters, vibrant dialogue and lively shootouts are more fully realized than you’d expect from a film in this genre, and Lapeyre and Wilson’s tonally precise, exciting direction make “I Declare War” much more than a childhood lark.