At this year's GDC they announced the "Nocturnal" initiative. It's not a whole game engine, but rather a collection of useful utilities. Things like logging code, C++ object serialization, and a cross-platform performance monitor. Some of the utilities are Playstation 3 specific, but most are applicable to any modern game platform.
Much of this code would be right at home in a "Game Gems" book, but it's even better to have it freely available, on the web, with a BSD-style license. Good for you Insomniac!
Insomniac also publishes technical papers in a GDC-presentation-like format on their Game R & D Page.
Why do so many game companies share information like this? I think it's for a number of mutually supportive reasons:
- It's a form of advertising, to show off how smart and competent the developers are. This is helpful in attracting job applicants and impressing publishers and game reviewers.
- It educates all game developers, some of whom will eventually end up working for the original developer.
- It encourages other developers to share their technology, which benefits the original game developers.
- It reduces the value of middleware, driving down the cost of middleware.
And it's a lot of fun for armchair developers like me. Now if only we can get Naughty Dog to open-source their GOOL and GOAL Lisp-based game engines. :-)