That's pretty contradictory with the description of Scrolls, specifically this part:
"Scrolls requires an Internet connection to play. Scrolls includes single player challenges along with online competitive and casual play."
If Scrolls is like Minecraft, you download the resources (minecraft.jar), but it doesn't unlock until you give your serial to a Mojang server. So in this case it may not truly be DRM-FREE, hence the download icon.
In a few short hours this Humble Bundle of Trash has sold 7000 more copies than playinjector's last bundle which was full of playable, DRM-free games.
Also scary that the avg is $6.39, therefore they've made about $42k in the last two hours. Not too shabby for card games with IAP.
They do have IAP, right? I mean, they're card games after all, they are meant to suck your wallet dry. A bit like this thread... Good thing this thread doesn't have IAP, right? Uhhh....
Why are there moths in my wallet? Where'd my cash go?