It's been a week since Blacksmith Games launched its Appvent Calendar.

A neat marketing idea, it enables 24 developers to each give away a game for free on a daily basis.

So far, Craneball Studios has given away its line drawing game 33rd Division, Kalio its tower defense game Tridefense, Alfonso Bozzelli his casual Snorkeling, Hexage its puzzler Totemo, MadFingerGames its actioner Samurai: Way of the Warrior, and today LeftRight Studios its smackBOTS.

A good section of genres then, although few of the games are high profile or have previously been best sellers; presumably that's one of the reasons they're being featured in the Appvent Calendar.

It certainly seems to be working as a marketing idea though.

33rd Division entered the US Free Top 100, while Hexage tweeted that Totemo has done 65,000 downloads worldwide, hitting #29 spot.

And at time of writing, smackBOTS is at #56.

It's less clear however whether this free popularity has transfered into significant paid sales after the event.

Still, as Appy Entertainment's Paul O'Connor pointed out in his recent column entitled The reason iPhone game developers are becoming digital retailers, the trend of offering different discovery options for the sale of iPhone games is only going to increase as the App Store gets more jammed up with apps.