To get the 50% discount, enter the coupon code of OCTOBERFEST when purchasing the game. This only applies to non-Game Club members. If you are a Game Club member, you can get some cool free stuff instead depending on how many games you purchase. Details can be found here.
I'm an Indie game developer with a couple of titles under my belt. I've been programming for 23 years on a variety of platforms. Currently I'm using BlitzMax, which is great.