A code available from your HIB2 download page will add Machinarium, Osmos and Braid, to your Steam account immediately, while Cortex Command and Revenge of the Titans will be added when they become available on Valve's digital distribution platform.

"We have a few hundred thousand Steam keys so we probably have enough to cover the whole promotion, but just in case, you might want to buy the bundle now," Wolfire explains. "If we run out of keys, there's no guarantee that we will be able to get more."

The games can also now be added to account on ModDB's platform Desura. By default, though, they of course come as DRM-free downloads direct from the Bundle site for PC, Mac and Linux.

The original Humble Indie Bundle also recently scored Steam activation, for all games.

At the time of writing, 158,217 Bundles had been sold, raking in a staggering $1,172,126.24. By default, the money is split between the developers, charity Child's Play, the EFF and Wolfire, though purchasers can adjust this as they see fit. The half a million mark was hit in under 24 hours.

As if that weren't all exciting enough, the Bundle will now be available for purchase until 6pm EST on December 25, having originally due to cease on December 21. After that, it's gone, so you still best get your skates on if you don't want to miss out on a stonker of a bargain.

If you fancy learning a little more about the Bundle's games, Wolfire was also taken a 'design tour,' casting a developer's eye over the titles: