Porting Games Across Consoles and PC

The biggest factors are the collections of libraries, tools, and engines in use.

If a game is built with Engine X, and the engine also runs on the target platform, you can generally reuse the vast majority of your code.

If your game is built with an engine that is not available on the target platform, be prepared for a long, hard, difficult, expensive road.


Assuming you have an engine that is already cross-platform, or work for a company that has developed their own cross-platform suite, it is easiest to go: PC, X360, PS3, then cutting to make it fit on Wii. Alternatively, put the Wii first because it is smallest, then you know the other platforms will have loads of room.

The X360 is basically a specialized PC. The PS3 is a major departure from the PC, but assuming you are talking about C or C++ code majority can be untouched. The only things that need to be adjusted are OS-level calls, and hopefully those are isolated to within your engine and libraries. The system libraries are obviously different between the platforms, but a good engine or intermediate library will hide that from you.

The Wii is a significantly slower processor with significantly less memory. It is easy to get lazy on the bigger platforms with unnecessarily large data structures and unnecessarily slow algorithms. Performance and memory size can be a concern because of those issues.


The same is basically true across the field: X360 and PS3 both have their own graphics systems with roughly similar functionality. The Wii has its own with substantially less. The first two support high definition video, the Wii does not. Both X360 and PS3 have similar controllers, the Wii is different. X360 and PS3 support high capacity discs, the Wii supports DVD. Etc.


So getting to your numbered questions:
1) Differences are significant, the ease depends on your engines and tools
2) Differences are significant, and it depends on your engines, licensing, and money
3) If your engine is already cross platform, >99% of code can be used on all three. Art is a different issue entirely.
4) Difficulty is entirely dependent on the engine and technologies. It is fairly common for established companies to have a code base that always runs on all four platforms.
5) Genre is not one of the most significant factors. The genre can be modified to stated performance requirements, visual requirements, user interface and input mappings, and so on. Those are important factors, but are still small relative to the engines and technologies being used.

These days about half of the major developers use middle ware which does the cross platform for them. It's pretty difficult to support all the platforms in a scalable fashion since they each have their strengths and uniqueness (Wii unique controls, PS3 Cell processors, etc..)

The PC and Xbox are the most compatible and porting to and from them is relatively easy (both use a windows OS, direct X, C++, etc..).

The PS3 probably is the most technically challenging to work with from that bunch, just due to the Cell processors.

The Wii is the least powerful and that brings it own constraints with its controller.

Unless your a large studio and have the investment to create an engine from scratch, multi-platform isn't really an option, without going the middle ware route. The problem with middle ware is that to support all the platforms they sacrifice platform specific features which can't be emulated on the other platforms.

That is why you don't see the advance post process fx (which use the cell) in games like Uncharted 2, Killzone 2, GOW3, etc.. on multi-platform games (just not cost effective to do one off features within a multi-platform middle ware).

Some games are just not possible to port depending upon the control schemes. People have tried porting RTS to consoles, but they have always been lackluster (due to loss of fidelity without a mouse). FPS work well enough on the consoles (with aim assistance and other modifications). To date no MMO have been even attempted on the consoles (there is the upcoming DC universe which is also coming to the PS3), probably due to their very heavy UI requirements.

Wii games utilizing the Wii Mote of course is impossible to duplicate on the PC or the other consoles without a motion controller ( like the PS3 Move or Natal ).

But things are looking up motion control wise, with the PS3 Move and maybe Natal, the consoles will finally get an accurate control device which might allow for new genres to be ported to the console.

-ddn