It wasn't supposed to happen like this.

Emotiv Systems threw a press conference in San Francisco this week to show the latest enhancements to its futuristic gaming system, which lets players control objects on the screen using only their thoughts.

When it works it can be impressive. The system is based on a "neuroheadset" fitted with about a dozen sensors that read tiny electrical impulses that are emitted by the brain when a person thinks. It learns to recognize the impulses and interpret thoughts like "up," "down" and "rotate" and translate them onto the screen.

On Tuesday evening the lights dimmed in a packed auditorium at the Sony Metreon theater and for a few moments everything went fine. An employee donned the headset and made facial expressions -- smiles, winks -- that were reflected on the face of an animated robot on a large screen. The employee rotated a three-dimensional cube on the screen and moved it forward.

Then he tried to make it disappear. Then he tried again. Feet shuffled uncomfortably in the auditorium. "Can you make it disappear?" CEO Nam Do asked hopefully. Someone in the audience coughed. "Shall we move on?" Do asked. "I think we'll move on to the next thing." Then the cube disappeared. The auditorium erupted into applause, either from excitement or relief.

Then came the demonstration of an actual game. Zachary Drake, Emotiv's game developer, built the crowd's expectations. "This," he said scornfully, brandishing a wireless game controller, "this is a wonderful thing, and it does some things really well ... but lifting an object with your mind just leaves this thing behind."

That's when things went really wrong. The neuroheasdset didn't work, so Drake had to use the wireless controller he had scorned a few moments ago to navigate through the game. (The controller is also part of Emotiv's system, it turns out, and supplements use of the headset.) The controller didn't work very well either, however.

"Can you please switch off any wireless transmitters you may be using because right now we can't even get the wireless controller to work," Do asked the audience. But it was too late.

"Welcome to demo hell, folks," Drake said.

It was an unfortunate night for Emotiv, which has demonstrated the system successfully at the Consumer Electronics Show in January and at other venues. It worked fine during set-up on Tuesday afternoon, Do said.

The IDG News Service is a Network World affiliate.