All of the games are available on Desura, and are being offered to get support for Steam Greenlight.
According to Indie Royale, "At Indie Royale we really want to support Indie Developers and we think that helping them to get popular support on Greenlight is great for them. We're going to start this bundle at a lower price - $2.99 - than usual and we'll keep it there for the first 24 hours of the bundle. That's a saving of over 90% to their total price separately. Buy the games and then support the developers on Steam Greenlight."
In addition, "The bonus target is $6 to get all the games plus the the ZX Spectrum chiptune album Microsongs by Yerzemyey (available in FLAC and MP3)."
Gamers interested in the Debut 6 Bundle can visit the Indie Royale site.