The browser, labeled 21.0.1171.0, shipped Monday to Google's "Dev" channel.
Google maintains multiple "channels," or versions of Chrome, with escalating levels of stability and reliability. Dev is the least stable and earliest public build, but others include "Beta" and "Stable," the last being Google's tag for a final, production-grade edition.
The company announced it would last Thursday, but at the time would not pin itself to a date.
After the new Dev version is installed, Chrome will run in both Windows 8's traditional x86/64 "desktop" mode -- the half that resembles Windows 7's user interface (UI) -- and in the tablet-, touch-centric "Metro" mode, where apps run in a full-screen, or at best, split view, with minimal UI gewgaws.
Under Microsoft's rules, a browser must be chosen as the operating system's default browser by the user to run in Metro.
Chrome in Metro also includes Flash, courtesy of Google's long-bundling of the Adobe software with the browser. That puts Chrome in the same category as , which in Metro can also render Flash.
Even though Metro is supposed to be plug-in free, both Google and Microsoft have circumvented the rule by integrating Flash Player with their browsers.
Mozilla, which is working on a Metro-ized version of Firefox for Windows 8, and has , had mixed thoughts on the trend.
"We think there should be equal access to platform capabilities and while we encourage healthy competition, believe there should be no circumstances that give any browser an unfair advantage," said Asa Dotzler, director of Firefox, in an email reply to questions about IE10's use of Flash last week. "[But] if other browsers can bring Flash or plug-ins in general to Metro, then it doesn't seem to be a problem. But that isn't clear at this time."
Dotzler comment was made before Google rolled out the Metro preview of Chrome with Flash included.
Chrome's deviations from the norm also include a decidedly different take on the Metro UI.
As others reported Monday -- including ZDNet blogger -- Google has seriously strayed from Microsoft's Metro design guidelines for Chrome, to the point where it puts up a desktop-like context-sensitive menu in lieu of the standard Metro app bar, and adds a full drop-down menu accessed by clicking on an icon in the upper right.
The preview of Chrome on Metro supports the Windows 8 'Snap' feature, but deviates from the usual Metro UI.
Both would presumably bounce Chrome from Metro if the browser was distributed through the Windows Store, rather than as it is dispensed, as part of a download package to the Windows 8 desktop.
Microsoft's -- which developers must follow to get the green light into the Windows Store -- specifically bans some of the things that the Chrome preview currently does.
"Your app must adhere to the Metro style app model," that agreement states.
But Google's deviations won't keep Chrome from Metro because Microsoft has given browser makers -- and only them -- a free pass.
, including Google and Mozilla, access to the desktop's Win32 APIs (application programming interfaces) from within Metro on Windows 8.
The deal also lets browser vendors package the Metro versions with their desktop editions -- the former is more of a wrapper around Win32 code rather than a start-from-scratch Metro app -- which lets them sidestep the curated Windows Store, the sole distribution portal for Metro apps.
So while Microsoft's guidelines for Metro apps might bar Chrome from the store, Google doesn't have to follow those rules.
Google may also extensively modify Chrome on Metro before it declares the browser finished.
"Over the next few months, we'll be smoothing out the UI on Metro and improving touch support," said Carlos Pizano, a Google software engineer, in a blog post last week announcing the impending release of Chrome.
Google first acknowledged it was working on a Windows 8-specific version of Chrome in mid-March, about a month after rival Mozilla said the same about Firefox. But Google has now not only caught up, but also passed its rival; Firefox on Metro won't show in any form before mid-July, when Mozilla rolls out Firefox 14.
Users who want to try out Chrome's Metro browser can switch to the Dev channel by downloading the Windows edition from . They must also set Chrome as the default browser for it to show up on the Metro Start screen.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at , on or subscribe to . His email address is .
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