A good place to learn about MMS is with the "How to Create MMS Services Version 3.2" document found at:
You will also find a huge resource of documents for all kinds of MMS functionality there such as: "External Application Developer's Guide" and "Designing Messaging Applications for the Nokia UI".
To see a sample of SMIL, look at
Then, when you are ready, you can get the developement tools. What tools you will need will depend on what kind of Game you plan on making and what programing language you plan to use.
If you are writing a game to be played over the network (for example, from a web server) which will send MMS to mobile phones, then you will need tools from:
Very helpful sample code can be found in the MMS Java library at
If you are planning on writing a Java game to run on mobile phones which sends/recieve MMS, then look under:
For testing your SMIL, tools can be found at:
Using the Developer's Suite for MMS, you can make an example SMIL, encapsulate it in an MMS, and prepare that message for HTTP transport.
There is no sample of a "MMS game" specifically, but there are sample codes for MMS applications and Java games at the web pages given above.
There are all kinds of valuable resources through out