every game starts out as the handmade creation of the inventor, which eventually becomes a standardized and mass produced product; but sometimes the commercial versions of games are not available, too expensive, or just not nice enough
Nice little guide to building an IR transceiver - uses the USB port for stable 5V, but includes a link in the comments to a decent circuit diagram that uses a voltage regulator and therefore doesn't need the USB port for power.
a small device which plugs into a $20 prepaid mobile phone to make a GPS tracker. The Tracker responds to text message commands, detects motion, and sends you its exact position, ready for Google Maps or your mapping software