I helped the octogenarian aliens, now it's curtains for the world

Pistol-grip response unit in hand, David Usborne sets out to make things happen in a New York cinema

It is a regular cinema in Manhattan. The film is Ride for Your Life. The first clue that this is going to be no ordinary afternoon at the pictures is that the feature is billed to last less than half an hour; the second is the funny, gun-like things at the end of the armrests where the popcorn usually goes.

The lights go down and red, green and orange buttons begin to flash rhythmically at me from my gun; except it is not a gun but a "pistol-grip response unit" (so says a voice that rumbles all around the auditorium). This is the tool of the "spectator interface" (the words of the voice again, not mine) that is about to occur between me and the action on the screen.

So here I am at my first interactive movie. "Don't Just Sit There" was the message on the billing outside. The voice goes further: "Feel free to shout, scream, holler and generally raise hell." I feel a little inhibited about this invitation, as the audience is somewhat thin today. Actually, I am the only person in the theatre. Me, the voice and my response unit.

So off we go. The principle I understand. At key junctures throughout the movie, I am going to be invited to determine what happens next. On each occasion I will have three choices and should push the corresponding button. It is meant to be a voting system, of course, with the most popular choice in the audience determining each twist of the plot. But with only me out here, that part of the fun is going to be lost. All control is with me.

It is not much of a surprise, therefore, when, after about three minutes, my response unit starts flashing for no particular reason and the voice interrupts the action to inform everyone (no one) that I have been selected as the "most influential voter" in the audience. Just for a moment I almost feel proud, which is fine, because in all other respects I am lost.

The film's plot, or multi-plot, is based on a bizarre blending of a cross- Manhattan bicycle race, an invasion by aliens (who look like your grandparents but have a habit of vapourising) and the takeover of the world by a corporation, called BigCorps, that has its headquarters in the Guggenheim Museum. Since I'm blinded by the zaniness of it all, my choices are always arbitrary.

That is probably why I do so badly. Rather than a film, this is really a giant computer game. Indeed, the audience is presented with a challenge: earn points by making the right choices. If you clock up more than 11,000, the world will be saved; if not, it's curtains. My final score? Minus 400. (Apparently, I twice aided the octogenarian aliens.)

But the technology of the movie, made by a New York company called Interfilm, is impressive. When I make a choice, the continuation of the action is seamless. During the cycle race I am offered six different camera shots and asked to select one. And it is up to me to decide who wins and who loses. There are no hiccups or visible edits.

For Interfilm itself, however, it is a bittersweet time. Ride for Your Life is being shown in 24 US cities and the company is about to receive a patent for the interactive system. But it is preparing to sue Sony Entertainment, alleging that the company has reneged on a contract to produce another such movie.

Meanwhile, audience figures for Ride have been disappointing. David Gorrett, one of Interfilm's directors, says: "This is an especially brutal time for us. We think the technology is exciting and it has performed perfectly. But audiences have not reached our expectations."