Bit late in the game I know but I though it was also important to point out for any reading late in the game that the freemium (http://en.wikipedia.org/wiki/Freemium) model plays a BIG part in the success of this game too.
A free version lowers friction and allows players to invest time into it making conversion easier by the commitment already put in and the higher player volume alone (normally you only have to convert 1-10%).
It works for Google, it works for Runescape, it works for iphone apps and it worked for this (and many other products / services) game too ;)
eternalsyndrome
Leroy joined
Indie Game Developer, part-time Ninja and Founder / Lead Developer of Eternal Syndrome (ES aka the E). The E (as of 2010) creates phenomenal Web and Download games. We've also been know to dabble with game tool applications and other software products. Our current focus is on creating premium core games that work on multiple platforms and online.