Normally I am purely a retail gamer but every once and a while I'll deviate and download an Xbox arcade or PSN game Castle Crashers, Battlefield 1943, and now Orcs Must Die. If you haven't seen this game yet it's a mixture a normal wave based 3rd person view game where you have various weapons and spells to use and a tower defense game. There not much of a story to the game the basics/the whole thing is that you are the War Mage's apprentice and after he slips and smashes his head on some stones steps and consequently dies you must take over his job.
Tragic story aside, this game has some interesting gameplay due to it's interesting mixture of same types a trend that seems to be catching on and something I hope continues, another good mixture of simple game play would be StarJeweled. There are some downsides, the main one being the bane of every gamer's existence...the unlockable difficulty. something that too me isn't all to bad except there are achievement tied to that difficulty which can be annoying as hell. Anyway it's bullet point time...
Two final notes: One, this is definitely one to pick up for you arcade or steam collection. Two, if you plan to buy this game you may want to do some research into checking if the price is going down anytime soon.