Posted 07 March 2014 - 11:08 PM
The two big concerns are marketing and legal.
Depending on your location on the globe, there might be legal consequences. In some countries the legal IP protections require you file the paperwork before making public announcements. If you are part of a small business, studio, or other serious endeavor, consult a lawyer before you release anything just to make sure all your government filings have been completed.
And as Tom mentioned, if you are working for someone else, such as a publisher or a bigger studio under contract, releasing photos is a bad thing until you have cleared it with both their marketing department and their legal department. Some of these companies spend millions of dollars in an effort to make a perfect public announcement, and all it takes is a single slip on twitter or a single leaked image to spoil the announcement. That kind of accidental release has cost people their jobs. (Nearly cost me a job once, as I CC'd a contractor who I thought was involved but had instead decided to not work with us.)
Assuming marketing and the lawyers and bosses/partners give you the go-ahead, you still must think carefully about what you release and how you release it.
You should consider it in terms of the big-picture marketing plan. Releasing images too early can make people tire of your game. Some small groups have found that regular excellent screen shots showcasing their progress can bring potential customers flocking to the door with cash. A few very good images can serve as a teaser, exciting interest in the project. A mediocre image is likely to be ignored, or worse, bring some mildly bad press. A bad image can sour your brand and gain insults and online derision. Also if you plan on getting media attention later on, some reporters are always going to find the old images and use them in the headline, so make sure you can live with that. All of these are marketing concerns, so if you have somebody who you plan to work with for your product's eventual marketing, talk it over with them.
Brand theft isnt usually a big concern for releasing early images.