Inexpensive headsets that detect brainsignals allow you to play games using only your mind.
In the Force Trainer game your aim is to focus. Achieve the right brain rhythm and a fan switches on,
lifting the ball inside the tube.
the technique that enables such brain controlled games,
was invented early in the 20th century. It measures the electrical activity of neurons within
the brain via a set of electrodes affixed to the scalp.
According to Wikipedia:
The electric potentials generated by single neurons are far too small to be picked by EEG.
EEG activity therefore always reflects the summation of the synchronous activity of thousands
or millions of neurons that have similar spatial orientation, radial to the scalp.
Discovers ''The Brain'' Spring 2010 issue digs a little deeper in an article about ''Games that detect brain signals'':
NeuroSkys hardware was developed by Burford Furman  and students of San Jose State University.
NeuroSkys breakthrough was its ability to read brainwaves, without the electrically conductive gels and the clunky,
unattractive (and expensive) headset that laboratory EEG requires.
Neuroscientist Majid Fotuhi  collaborated on developing the toy: The games software is able to decode a players
state of mind because the ''concentration'' and ''meditation'' electrical states are broadly distinguished from
each other, and those states influence the entire front of the brain.
The strength and distinctiveness of the two signals mean that the toy can employ just one forehead EEG sensor
rather than the multiple electrodes used in the lab.
Still, the headset might seem a little awkward, as it need a second skin contact, either on the ear or behind it,
to help filter out background signals.
And certainly, more sensitive headsets will someday allow for more elaborate games.