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Hello!
Switcheroo.
• (session based on new project) + (bureaucracy) = trouble
with Grant Skinnerbuilding multiplayer games
with Grant Skinnerbuilding games in silverlight
about this talk
• microsoft platform• market opportunities• skills required• technology• challenges• Q&A / discussion
Market Opportunities
65%
35%MALE
FEMALE
20% AGR & accelerating
Online Casual Games
$600M $2.1B2007 2008
Downloadable Casual Games (PC)
$490M $835M2008 2009
Social Games
FarmVille by Zynga
• Primarily played through Facebook
• 5 weeks to develop• 1M users in first 4 days• 82M users in 9 months• Est. $200M+ revenues
from micropayments, ads, & offers in just 2 years
FarmVille
• Direct sales to consumer• Sale / licensing to
distributor• Advertising (in-game &
banner)• Premium subscriptions• Micro transactions
(fastest growing segment)
• Indirect: marketing, services, component sales
Revenue Breakdown 2010*
Monetization
• dedicated game development companies, including mainstream game companies (ex. EA)
• marketing agencies & interactive shops building branded properties
• casual developers working for fun / free. There is a move towards “publishers” funding games.
Who builds these games?
• Currently owns social games market (MySpace distant #2)
• 70% games played outside US
• FB Connect biggest driver• FB Credits coming soon• Average player is 35+• Currently growing at 10%
Game developer qualifications
Game development is one of the best ways to expand your abilities as a developer, but it requires a special type of developer.
Multiplayer Game Development
Game Development
Application Development
Game development
Optimization
Holistic optimization of performance and memory. Encompassing code, graphics, architecture, and algorithms.
Code optimization
Syntactical and structural optimizations start with a good understanding of the compiler, runtime, timing model, and GC.
Profiling tools for Silverlight include XPerf, Silverlight Spy, Eqatec Profiler.
Graphics optimization
Game developers need to look beyond code, and understand the performance implications of graphics and animation.
For example, the relative impact of vector vs. bitmap vs. cached art, understanding GPU acceleration, and the cost of shaders and 2.5D effects.
Creative architecture
Due to the performance critical nature of game logic, you often must make practical trade-offs between architecture and performance.
Abstraction and low coupling often come at the cost of some performance overhead.
Algorithms
Games frequently rely on performance critical algorithms for tasks like path finding, proximity detection, spacial division, data manipulation, and physics simulation.
An understanding of algorithm growth rates, and the ability to utilize / analyze / adapt existing algorithms is critical.
Math
At a bare minimum, you will require basic knowledge of elementary math, spatial math, bitwise operations, and trigonometry. Advanced trig and some calculus or physics can pay off as well.
Things get vastly more complicated when you move into 3D. Hello quaternions!
Game experience
In game development the user experience is more tightly bound to development than in RIA development. This means the developer must have a genuine interest and aptitude in creating quality gameplay.
Graphics & sound integration
• Graphics and audio are much more closely tied to development in games than in most applications. It also tends to be a much tighter iteration process.
• You will want to be very familiar with the import tools in Blend. Knowing a bit about the tools your designers are working with is also helpful for quick tweaks.
Interaction & display
• Games tend to require more granular control of interactions (mouse & keyboard), and the display.
• For example, limitations with mouse leave, tracking key down state (ex. KeyHandler), handling key repeat, etc.
Spiking
The process of creating small, isolated tests is broadly useful in development, but is especially applicable to game development.
Silverlight / VS is not particularly suited to spiking, but we’ve found some approaches that work ok.
Spiking: Approach 1
1. Create solution in VS for your spikes & add any shared class libraries
2. Create a web project, and set its start action to “current page”
3. Create new spikes as new projects in the solution.
Launching the project will display the project directory in IE, allowing you to select a spike quickly.
Spiking: Approach 2
1. Create a new project for your spikes.
2. Create each new spike as a UserControl.
3. Switch the RootVisual for your application either in code.
Similarly to this, you can simply load in your spike as the primary child of a simple harness app, and change it at runtime.
Programmatic motion
There are a lot of ways to move elements around on screen. Understanding the pros and cons of each, and being able to implement them is a must.
Ex. programmatic eases, linear, simple, acceleratory, cartesian, vector / angular.
Collision Detection
Most game types require collision detection. There are multiple approaches:
rectangular, point to shape (VisualTreeHelper.FindElementsInHostCoordinates), mathematical, & shape to shape (w/custom shader).
Multiplayer game development
Models
• Server as host: The server manages game state and handles all significant logic. Clients act as views.
• Client as host: One client is promoted to host / super client, and owns the definitive game state.
Turn-based asynchronous / social
Interactions between players are asynchronous or have minimal intersection. The game continues across multiple sessions. It may have alternating or adhoc “turns”.
Generally more traditional networking approach (http, request based). Requires separate messaging. Game state lives on the server and must be maintained for the life of the game.
Turn-based synchronous
Players alternate turns in a single gaming session.
Can use either http requests & polling or socket connections. Latency has little impact. State can live on the client or on the server.
Real time
All players are active simultaneously, and can interact with each other in real time.
Clients communicate through a socket server. Latency management is critical. Game state can live on the client or server.
Be very careful with random and time based logic.
Real time messaging
Typically broken into 3 message types: interactions, game events, and state updates.
• Interactions - disseminate user interactions to server / clients• Game events - notifications of significant game events• State updates - full or partial state information
Handling latency
Latency will generally range from 60-300ms (client to server to client). Better connected and more localized servers will reduce this. Server based game logic also greatly reduces the impact of latency.
Dealing with latency involves strategies like delaying user inputs to account for latency, interpolating values based on known / estimated latency, and making interactions “fuzzy” to reduce obvious discrepancies.
Minimizing cheating
Gamers will spend an unbelievable amount of energy hacking popular games. Packet sniffing / injection, decompiling / modifying / redistributing your game client, etc.
This can be minimized by keeping more logic on server, random checks, client “honesty” heuristics, and obfuscation.
Technology
Java is (surprisingly) still in use, but is rapidly losing ground to Flash, the market leader. Silverlight is the new kid on the block.
Lack of tooling / support for animation & interactive design
Higher barrier to entry for users & developers
Larger file size & slower initialization
Version fragmentation, complicated runtime distribution
Security considerations
Java’s downfall
Flash’s strengths
• Ubiquity• Very low barrier to entry for developers & users• Strong toolset for animation, interactive design, & development• Simple run-time updating• Robust, approachable language• Good code performance, reasonable graphics performance• Very strong & vibrant community, lots of OSS code incl. game frameworks• Portability to AIR, mobile, devices
Strengths: Development
• Robust language & excellent developer / debugging tools
• Server-side integration
• Access to mature game libraries & commercial components
• Some XNA libraries can be used via Silversprite (and similar projects)
Strengths: Performance
• Code execution• Multi-threading• GPU support (limited)
Strengths: Portability
• Portability to Windows Phone 7, XBLA, WPF• Very simple out of browser experience• Easy to move to native desktop application
Thank you!
@gskinner
gskinner.com/blog/
Questions?
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The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions,
it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.
