The transformation of Digital Chocolate continues apace.

Starting out as an mobile publisher, it quickly adopted iPhone but now is focusing on Facebook games (while still releasing for those other platforms of course).

In his latest blog post, CEO Trip Hawkins reveals that Digital Chocolate has surpassed 1 million monthly users for its social Facebook games.

"Last week, there were only 10 games with virtual goods that added at least 50,000 players and that grew by more than 20%. We had two of the 10," he says of the company's MMA Pro Fighter and NanoTowns.

More games, more social

Since then Digital Chocolate has released Safari Kingdom, with Hawkins' big new hope, the first game in the NanoStars series due soon.

"I'm really enjoying the final stages of polishing NanoStar Castles, which I began playing and tuning in a prototype form almost two years ago," he says.

And indeed he is. As the prolonged playtest we experienced at GDC 2010 demonstrated, this is a product Trip feels very strongly about.

"This has been a labour of true love and I hope people give it a serious look to appreciate the many innovations and subtleties," he explains.

NanoStar Castles will be out on Facebook at the end of March. It will be released on iPhone at some future point too.