If you haven't already played Immortal Defense -- known around the Burch household as "the single best tower defense game ever made next to Plants vs Zombies" -- you're in luck. In celebration of his own birthday, creator rinkuhero has dropped the price of his metaphysical epic from $15 to $3.
Go here and enter "BMCN000H7" (without quotes) as a promo code. You won't see the price reduce until you click "confirm order."
All proceeds presumably go toward funding Saturated Dreamers, rinkuhero's next project. You can find out more about the game at its Kickstarter page, but suffice to say it's a top-down exploration game about a big-ass alien lake. Such a cliche, I know.
Anyway, I highly, highly, highly recommend getting Immortal Defense while it's this cheap. Regardless of whether you tend to like tower defense games or not, ID remains unparalleled in its satisfyingly minimalist design and surprisingly well-written story. Act quickly, though: according to the email sent to me by rinkuhero, the sale ends September 30th (alternately, IndieGames.com says Oct 4).