Waterloo Labs is a group of engineers that work at National Instruments. They work closely with other enginerds that live in Austin, TX.
In this project they used a big screen with acceleerometers that senses impacts on the screen. After feeling the impact, it will trigger an action on the game Half-Life. Waterloo Labs even hired a shooting instructor to shoot guns at the enemies at the games.
Not to be left out, the enginerds decided to hit the board with a shovel which acts as an axe in the game. I actually laughed out loud while watching this.
Waterloo Labs’ blog has the code to complete the demo yourself and has a list of parts. There is also an explanation of the math on how this works.