If Andy Samberg — the real Andy Samberg — pulled up in a limousine and told you to get in, what would you do?

Tommy, a man-child approaching middle age, chooses to take the ride, and his life becomes suddenly more interesting in writer-director-star Jake Johnson’s “Self Reliance,” which functions as a slight but amusing twist on David Fincher’s 1997 film “The Game.”

Johnson (“Drinking Buddies,” Fox’s “New Girl”), making his feature film directorial debut, stars as Tommy, a fellow still getting over the fact that his girlfriend (Natalie Morales) left him after 23 years because “your version of being together is ‘existing,’ and I needed more from life,” she says.

Indeed, Tommy is stuck in a rut. So when Berkeley native Samberg, playing himself, rolls up in the limo, getting in seems like a good idea. Turns out, Samberg has been paid to deliver him to a seemingly abandoned warehouse on the outskirts of Los Angeles, then disappear.

Tommy enters the warehouse to find two men who are running a reality game “on the dark web.” The premise: If he can survive 30 days without being killed, he gets a million dollars. The loophole — and the key to survival — is that his would-be assassins cannot murder him if he is with somebody.

Thus the emotionally aloof loner must invite human contact. First, he pays a bum (Biff Wiff) to be his companion. Later, a fellow game player (Anna Kendrick of “Up in the Air,” the “Pitch Perfect” movies and “Alice, Darling”) joins him.

Meanwhile, Tommy’s family, including his sisters (Emily Hampshire of “Schitt’s Creek,” and Mary Holland), brother-in-law (Daryl J. Johnson) and mother (Nancy Lenehan), become increasingly concerned about his mental health as he describes his adventures with bounty hunters and celebrities (Wayne Brady also appears as himself).

Johnson is, as always, an engaging presence, playing Tommy as a haggard everyman whose journey to self-awareness is amusingly hard-won. There are many laughs in “Self Reliance,” but overall the story is somewhat predictable and peters out to an unsatisfying resolution.

A hint at a deeper direction Johnson could have taken is the all-too-brief reunion with his long-lost father (Christopher Lloyd in a wonderful cameo). How many of Tommy’s problems stem from his father’s abandonment? How has it affected his family? Unfortunately, we don’t find out.

Still, this is one of those projects in which everyone on set seemed to have fun making a movie. That joy comes through, even if the finished film induces a good-natured shrug.

Reach G. Allen Johnson: ajohnson@sfchronicle.com