This discount offer is still valid but it's only for direct sales - I don't have any way to give out discount codes or coupons on Steam. (At least, not that I've ever found.)
Of course, buying a direct copy entitles you to a Steam key as well. They're not automatic (technical reasons), you have to ask for one, but if you buy through my site you CAN get your achievements and cards eventually.

However, if you're hoping to use Steam's purchase system/wallet/etc then that won't help much.
As far as upcoming discounts go, there will probably be some sort of game giveaway contest in August/September themed around our latest game, Black Closet, and free copies or discounts on other games will be possible prizes.
It's also likely to come up on the weekly discount rotation on Steam at some point but weekly sales are generally only small discounts and I don't have an actual schedule for that, so I can't tell you when atm. I think if you wishlist games you get notifications if they go on sale there?
I got sort of rambly, hope this helps!