He named the site Kongregate.com and in June began inviting game developers and players to test it. At the end of 2006, he opened the site to people of all stripes, who can create, submit and play games free of charge.
So far, the advertising-supported site offers 300 games that are rated by players, who chat online as they play.
"Not all of them are gems, but the top 100 are," said Greer, 36, who founded the company with his sister Emily, 32, and offers game makers a share of the site's ad revenue.
Reed Hoffman, founder of business networking site LinkedIn and a former PayPal executive, said timing played a big role in his decision to become an investor in the company.
Adobe Systems' Flash software, which is used to make those Web ads that wiggle and shake, has made it easy for developers to quickly churn out fun games. At the same time, advances in Web technology have spurred all kinds of new ways to rate and share information online.
"If you get thousands of people creating content, really interesting things emerge," said Hoffman, an occasional gamer who said that while 70 percent of amateur games tend to be stinkers, about 10 percent are great.
Greer, 36, is not new to the $30 billion global business.
He started making games on his Apple II computer when he was 12 and his first job was at Origin Systems, where he worked on several iterations of the company's Ultima games.
Greer was most recently technical director at Electronic Arts' Pogo.com Web site, where more than 14 million mostly middle-aged females play word, puzzle and card games monthly.
Kongregate debuted amid rising interest in independent games. Developers have more avenues than ever to distribute such products--from Shockwave.com and AddictingGames.com to new entrants like Microsoft'sonline game service.
Rival console makers Nintendo and Sony are also preparing to launch their own indie game outlets.
Alabama college student Brad Borne, 21, made The Fancy Pants Adventures, a "goofy and cartoony" offering that's one of the top-ranked titles on Kongregate.
The easy-to-play and addictive game stars a stick figure in big yellow pants.
Borne said he made his first full game SnowBlitz when he was 19. He has lots of other ideas percolating, is working on a follow-up to Fancy Pants and is a Flash game programmer for hire.
He said his daily share of advertising revenue from Kongregate is about $2 a day--which he expects to increase as traffic grows--and is a big fan of the site's live chat.
"It puts a name and a personality behind your audience. It does the same thing for developers," said Borne, who said players have given him good ideas for the his Fancy Pants sequel, which he's testing on Kongregate.
He hopes one day the experience will take his career to a new level, but said he has something else to finish first.
"I'm just taking it one step at a time," he said. "After college I'll see what I can do with it."