In Verbis Virtus is an upcoming first-person action/puzzle game that makes use of speech recognition in a rather interesting way. If you want to cast a spell, you're going to have to actually say the words. Should you succeed in pronouncing the words correctly, you'll be able to make use of the associated spells to overcome traps, solve puzzles and kill enemies. The developers are currently working on the first episode of the series. However, if you're curious as to how it all works, there's a handy demo available on their website.

Those interested in learning more about the game should head down here.