Best Practices in Game Design for the Ultra-Mobile PC

The Ultra-Mobile PC (UMPC) expands the market for PC games that run on Microsoft® Windows® XP, as long as developers consider certain design requirements to ensure a good user experience. In most cases, a single version of games can span both the UMPC and traditional PC platforms.

The Ultra-Mobile PC (UMPC) platform is of increasing importance as a target system for game developers. Because these systems run on Microsoft Windows XP Tablet PC Edition, they don’t require a full operating system port for existing games, but the UMPC form factor does introduce a number of unique considerations in game design. For example, UMPCs typically have a touch screen with an 800x480 or 1024x600 resolution, which are small pixel sizes and unusual aspect ratios. Developers must also accommodate alternatives to conventional keyboard and mouse user interaction, and a CD-ROM drive is typically not available. See the sidebar, Typical UMPC Hardware.

The best practices in this document for enabling PC games to run successfully on the UMPC platform are based on an analysis of a large number of PC games currently on the market. Those games were executed on a UMPC to identify common strengths and weaknesses associated with the platform, as well as specific game-design factors that contribute to the best user experience. The analysis includes design considerations for providing high-quality games on the UMPC, as well as common issues associated with providing UMPC support, providing best practices to resolve each of those issues.

Screen-Size Considerations

Because the UMPC screen is much smaller than a traditional screen, the size of graphical elements must be handled with some care. Developers must avoid making scaled-down graphical elements too small, as well as allowing elements that are left the same physical size to consume too much screen space. Specifically, text and icons are often hard to see clearly, some buttons or units are difficult to click reliably, and some game windows do not fit entirely onto the screen.

Text and Icon Sizes

Issue: In the interfaces of games that are ported to the UMPC, text or icons may shrink to a size where it becomes difficult to see them clearly. This prevalent issue is important to avoid, because text and icons become useless if they cannot be read or differentiated. Text that appears reasonably sized on a 15” screen can easily become too small when shrunk to a five- to seven-inch screen that you might find on a UMPC. Aside from the actual font size of text, chat and other text windows may become too small. Accommodating smaller window sizes by decreasing the font size can make the text difficult to read.

Best Practice: Ideally, games designed with the UMPC in mind should use text sparingly and consider the UMPC screen size when choosing a font. Likewise, icons should not rely heavily on fine details, so different objects are different enough to be easily distinguished from one another, even on the smaller UMPC screen. In places where increasing text size enough would compromise other elements of the game, allowing text size to be adjustable may be a good solution, allowing individual players to decide for themselves the ideal size for the text.

Clickability of Buttons and Other Elements

Issue: Similar to the issue of small text, buttons and other clickable game elements add complexity to porting games to the UMPC. While the overall interface on the UMPC must be smaller than the corresponding standard PC version, the actual buttons in the UMPC interface must be larger, in order to accommodate being accurately clicked by a stylus or finger, rather than the more precise mouse that is used in the standard PC version. This issue is particularly acute when multiple buttons or other elements are clustered together, which makes it more likely that the user will select a different element than the one they intend. Even when it is possible to select the correct element with some care, this issue can significantly detract from the user experience.

Best Practice: As with the size of text and icons, game developers should avoid this problem by using large, distinct buttons and other elements. These elements should also have enough space between them, making it less likely that the user will inadvertently select the wrong one. In those cases where a text label appears adjacent to a button or other element, that label should be part of the clickable area associated with the element, making it easier to click without having to devote any additional space.

Game Window Size

Issue: If game windows use a fixed size, rather than automatically resizing themselves to fill the full UMPC screen, parts of the game may not be visible all at once, and, in some cases, certain parts may not be reachable at all, as shown in Figure 1. This situation is made more complex by the potential for players to use the 800x480 or 1024x600 resolution enabled by the UMPC’s wide screen, since those aspect ratios must be matched to the standard 4:3 aspect ratio employed by most PC games.

Best Practice: The key to resolving this issue is for game developers to consider the 800x480 and 1024x600 resolutions as they develop game interfaces for the UMPC, shrinking the entire game to fit on the screen or rearranging the interface to take full advantage of the wide screen area. Certain simple accommodations can make games more playable, even in a truncated state. For example, providing scrollbars and allowing the window to be resized (manually or automatically) may be sufficient in some cases to allow the user access to all parts of the screen and to provide an acceptable user experience, particularly for browser-based games.

By: Michael Finkel

Michael Finkel is a Technical Marketing Engineer in the Ultra Mobile Group at Intel® Corporation. Michael has been with Intel since 1998 and has worked on graphics software and optimizing performance for a variety of platforms ranging from handhelds up to servers. Michael is now focused on the definition and implementation of Ultra Mobile PC platforms.

michael.finkel@intel.com

By: Matt Gillespie

Matt Gillespie is an independent technical author and editor working out of the Chicago area and specializing in emerging hardware and software technologies. Before going into business for himself, Matt developed training for software developers at Intel Corporation and worked in Internet Technical Services at California Federal Bank. He spent his early years as a writer and editor in the fields of financial publishing and neuroscience.

matt.Gillespie@intel.com

By: Victoria Bailey

Victoria Bailey is a Senior in Computer Science and German at Oregon State University. In Summer of 2006 she took part in an internship at Intel in Folsom, California, where she wrote this article. In the future, she plans to attend graduate school for Computer Science.

This article also appears on www.intel.com/software/mobile and is reprinted with permission from Intel Corporation.