27XNA is based on Microsoft ’s C# language and the Common Language
Runtime (CLR). The primary development environment is Visual Studio or
its free counterpart, Visual Studio Express. Everything from source code
to game art assets are managed within Visual Studio. With XNA, develop-
ers can create games for the PC platform and Microsoft ’s Xbox 360 console.
Aft er paying a modest fee, XNA games can be uploaded to the Xbox Live
network and shared with friends. By providing excellent tools at essentially
zero cost, Microsoft has brilliantly opened the fl oodgates for the average
person to create new games. XNA clearly has a bright and fascinating future
ahead of it.
1.5.5. Other Commercial Engines
There are lots of other commercial game engines out there. Although indie
developers may not have the budget to purchase an engine, many of these
products have great online documentation and/or wikis that can serve as a
great source of information about game engines and game programming in
general. For example, check out the C4 Engine by Terathon Soft ware (htt p://
http://www.terathon.com),,) a company founded by Eric Lengyel in 2001. Docu-
mentation for the C4 Engine can be found on Terathon’s website, with ad-
ditional details on the C4 Engine wiki (htt p://www.terathon.com/wiki/index.
php?title=Main_Page).
1.5.6. Proprietary in-House Engines
Many companies build and maintain proprietary in-house game engines.
Electronic Arts built many of its RTS games on a proprietary engine called
SAGE, developed at Westwood Studios. Naughty Dog’s Crash Bandicoot, Jak
and Daxter series, and most recently Uncharted: Drake’s Fortune franchises were
each built on in-house engines custom-tailored to the PlayStation, PlayStation
2, and PLAYSTATION 3 platforms, respectively. And of course, most commer-
cially licensed game engines like Quake , Source, or the Unreal Engine started
out as proprietary in-house engines.
1.5.7. Open Source Engines
Open source 3D game engines are engines built by amateur and professional
game developers and provided online for free. The term “open source” typi-
cally implies that source code is freely available and that a somewhat open de-
velopment model is employed, meaning almost anyone can contribute code. Li-
censing, if it exists at all, is oft en provided under the Gnu Public License (GPL)
or Lesser Gnu Public License (LGPL). The former permits code to be freely used
1.5. Game Engine Survey