SF-based casual game publisher PlayFirst has received $5 million in its second financing round, led by Rustic Canyon Partners. Existing investors, including Mayfield Venture Partners and Trinity Ventures, also joined the round.

The firm originally formed in late 2004, with initial first round funding of $5 million...the company is led by co-founder and CEO John Welch, formerly one of the leading lights behind Shockwave.com’s gaming portal.

MercuryNews: PlayFirst has published seven games for the casual market, where consumers download games from web sites for free trial and then have the option to buy them. Its biggest hit is “Diner Dash,” which has sold more than 200,000 copies.