Flash websites are absolutely drenched in simple tower defence clones, but Tesla Death Ray takes the whole genre a bit more literally. You play as a tower, and you must defend yourself - by blasting lightning at your foes and eviscerating them.
The best part of Tesla Death Ray is the sounds the soldiers make when you brutally electrocute them to smithereens. Now that may sound a little morbid, but it's such an awesome feedback device, and it makes the game compelling. No matter how long I played, it remained fun to melt people and when you combine this with the mechanics of building up your single tower, Tesla Death Ray becomes quite the functional little time waster.
Tesla Death Ray [Kongregate]