To channel an unhinged cat lady, Isabelle Huppert wears pointy mustard mules. To embody a diva courting eternal youth, she wears electric purple pumps embellished with crystals. In the business of character building, these are very important details, even if the character appears only once, in a minute-long scene.

Six of these scenes make up the Roger Vivier spring 2021 presentation video, released on Oct. 1. This season, Gherardo Felloni, the creative director of the house, was unable to create the sort of freaky fashion fantasy hotel that he did in Paris in February. So he made an interactive movie instead.

It’s a choose-your-own-adventure game, with Ms. Huppert cast as a devious game master. At the end of each short scene, she gives viewers a choice; if they choose correctly, they move on to the next scene. Each pays homage to genre films like “Batman Returns” and “Death Becomes Her.” (Choose incorrectly and the scene plays from the beginning.)

To Ms. Huppert, 67, the project seemed like an inventive take on a shoe ad. But it also reinforced for her the power of costuming. During filming, for example, she was presented with a dress she’d worn before, in “The Lady of the Camellias,” a film made nearly 40 years ago. Freshly dug out of storage, the costume brought back memories — not of 1981, but of becoming that character.

During a call from Paris last week, Ms. Huppert said that “costumes are essential.” In the edited conversation below, she elaborated on the connection between her clothes and her craft.

How does a costume help you get into character?

It’s really the first step to the character, the door to the character. And shoes are very, very important because they define the way you move. When I was playing the bitchy woman with the cats, I’m sitting and you can see my attitude in the shoes, in the way I’m keeping my legs close to each other.

A friend — when she was asked, “How do you find your roles?” — used to say, “in my shoes.” I think that’s so true. Whether you walk with high heels or with flat shoes or with tennis shoes, this is really where the character departs from. From the shoes.

Are shoes important to your personal style?

Yes, I’m a shoe person. A beautiful shoe, especially with high heels, gives you such an attitude. All of the sudden you can be very gracious or very powerful.

When you wear a pair of shoes for a costume, it’s not so easy to wear it again, because it’s so much connected to the role. So I’ll keep them more as a souvenir than anything else.

During lockdown, did you put your heels into storage?

Obviously. You don’t want to wear high heels in your own home — it was more like bare feet most of the time.

During the confinement, you let go of doing your hair and walking with shoes and even getting dressed sometimes. I tried to get dressed, just to keep up a rhythm.

So you weren’t like the rest of us, living in sweatpants and leggings?

Well, leggings are clothes in a way. But I got dressed, absolutely. I think otherwise it must have been very depressing. Why not stay in bed all day?

Why did you say yes to this project?

The Vivier house has an old story, but there is a sense of humor. There’s something witty about the shoes, most of the time, whether through the color or a detail attached to the shoe.

I also think the new designer is very talented. The script was very creative, and I had a certain pleasure as an actress to play all the different characters. It was easy for me, more so than if I had to play myself.

What made it easy?

I think the different costumes and hair. The exterior is influential on the interior. It makes you move differently, it makes you behave differently, and it makes you someone else. It’s as simple as this.