While knickers are being busily twisted about whether claiming The Binding of Isaac as in any way qualifies as a roguelike is right up there with the purest, most horrifying, most unforgivable evil of calling a real-time tactics game a real-time strategy game, let's also look at something that does fit that genre without outrage. This one's turn-based and everything!
Cardinal Quest, which impressed our Mr Smith just over a month ago, is spending 24 hours in the happy land of no-pennies. To qualify for this most absolute of discounts, you'll need to read this tweet from CQ's creator, Ido Yehieli and apply the code wherein when you go as if to purchase the game. That's it! Trailer below if you're having a dither.
If you want to give Ido some money for the game anyway - because it is a jolly good game - you can still do so by ordering again, without the code. If the whole ordering twice thing seems too confusing, you could always try the demo first and then pay for the full thing. Or just pay anyway. Or... I dunno. I'm out of ideas now.