Jake Johnson makes his feature directorial debut with “Self Reliance,” a comedy with a fascinating premise and an opening act that provides equal thrills and laughs. Unfortunately, while Johnson’s script shows promise, the actor/writer-turned-director squanders it with a lack of strong vision, and a rom-com element that makes the film lose focus, and also most laughs.

What if you take David Fincher’s “The Game,” but run it through The Lonely Island’s comedy filter? That’d get you close to “Self Reliance,” which starts strong but loses itself in an attempt to juggle too many tones at once. We meet Johnson’s protagonist, Tom, a man conforming to a sad routine he repeats every single day. He goes to the same bar, watches the same cowboy movies, and repeatedly tries and fails to knock on his ex-girlfriend’s door to ask her why she suddenly broke up with him.

Tom sees little value in his life, which is why he is especially thrilled when Andy Samberg — yes, actor Andy Samberg, who also produces the movie — shows up as himself in a limousine and offers Tom a chance at adventure. Granted, Tom has no idea what he’s signing up for. But he blindly gets in the car with Samberg anyway, agreeing to be taken to the middle of nowhere without a single clue as to where they’re going or what they’re doing.

The offer, as it turns out, is to participate in a Dark Web show where Tom has a chance to win a million bucks. The catch? He will be hunted for 30 days, and only if he makes it out alive will he get the money. Oh, and they can only try to kill him when he is alone. If Tom is in close proximity to any other person, his hunters have to stand down. Easy peasy, right? Well, Tom doesn’t count on his family blatantly mocking him when he tries to explain the deadly situation, and immediately leaving him alone despite his repeated pleas and warnings of the mortal danger he’s facing.

“Self Reliance” runs effectively with that setup, at first. The family dismissing Tom, his desperate attempts to stay physically close to his brother-in-law, and then a homeless guy Tom hires to shadow his every move are outright hilarious. Like Fincher’s “The Game,” though, it also knows when to turn up the tension once we see that Tom is not lying and there really are hunters after him. Also like that film, part of the tension comes in making both the characters, and at times even the audience, unsure whether they should trust the protagonist’s interpretation of the situation or not. Johnson knows how to mine humor from the absurdity of his script. The film is at its best when doubling down on the absurdity of its premise, finding excuses to send in assailants dressed as Michael Jackson and Mario from “Super Mario Bros.”

The problem is that, while Johnson crafted a good script that balances multiple tones, his directing isn’t as confident in that tightrope. Sure, there are moments of tension and comedy, but as soon as Johnson introduces a romantic element in the form of Anna Kendrick’s Maddie — someone who reaches out to Tom via a CraigsList ad and says she is also a contestant — the momentum comes to a halt. Almost immediately, the film pivots into indie rom-com territory, trading the outlandish premise and absurdist tone for a grounded and understated focus on the film’s themes about human connection and overcoming self-doubt.

Nothing wrong with this, of course, but the film fails to navigate that pivot in an effective way. As much as Johnson and Kendrick have terrific chemistry and their interactions feel organic, with each trying to one-up the other during the game, Kendrick’s character exits as abruptly as she enters the film. This makes both her character and her subplot feel like an afterthought.

“Self Reliance” is a showcase for Johnson’s everyman acting chops, as well as his ability to craft an interesting script, but the overall story and execution are underwhelming. The result is not Fincher’s “The Game,” but it certainly is not “Ride the Eagle” either.

Grade: C+