Conclusions
Valve makes a good case for its hybrid threading model, although it's hard to argue against using the most appropriate threading approach for a given task. Creating a programming framework that allows that kind of flexibility was apparently very difficult, but in the end, Valve says it will enable games that competitors who don't make the same investment in multithreading simply won't be able to match. Hybrid threading has also proven to be an asset in the company's work with Microsoft's multi-core Xbox 360 console, and Valve says it sets them up nicely for what they believe is a "post-GPU" era looming over the horizon. Interestingly, though, Valve noted that its model isn't particularly applicable to the PlayStation 3's Cell processor.

Valve intends to roll out hybrid threading enhancements in the next major Source engine update, which will be released before Half-Life 2: Episode Two ships. Those enhancements won't include the richer visual simulations, smarter AI, or more complex physics that are possible with multi-core processors, but dual- and quad-core systems should see a performance boost with Valve's existing Source-engine games.

Of course, the more intriguing potential of Valve's approach to multi-core gaming won't be realized until its game designers start developing titles explicitly with multiple cores in mind. Work has already begun on more complex particle systems, realistic physics, and smarter AI, and Valve may even release a short level—similar to Lost Coast—to showcase how the Source engine can exploit quad-core processors. That release may be the first glimpse we get of how multi-core processors can fundamentally change gaming. For years, we've enjoyed how the rapid pace of graphics hardware development has enabled ever more compelling visuals. Yet while developers have been able to create games that look real, their behavior has been anything but. Multi-core processors may finally give artificial intelligence, physics, and other game elements a chance to catch up.

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