Google this week took more steps in its scheme to aggressively lock down its Chrome browser by disabling most add-ons that weren't installed from its curated app store and banning plug-ins built to a decades-old standard.

Some users called the moves "lame***" and "the single biggest intrusion into not only my browsing convenience, but my computer usage I've ever seen in my entire life."

In a pair of announcements, Google said it is now enforcing rules it had set earlier that force users to obtain add-ons -- the popular gadgets and enhancements that users pile on their browsers -- from the Chrome Web Store. It also made some of the final moves to bar NPAPI plug-ins from Chrome.

Beginning Tuesday, Google began imposing a rule that required extensions, also called add-ons, to originate from the Chrome Web Store for the Windows browser. The change does not affect the OS X or Linux versions of Chrome.

The Chrome Web Store is Google's official distribution channel for Chrome and Chrome OS add-ons, apps and themes.

Google, which has been tightening the screws on third-party add-ons for nearly two years, has claimed that unauthorized and occasionally malicious extensions are a leading complaint from users and a prime cause of problems.

"From now on, to protect Windows users from this kind of attack, extensions can be installed only if they're hosted on the Chrome Web Store," Erik Kay, an Google engineering director, said in a May 27 blog. "With this change, extensions that were previously installed may be automatically disabled and cannot be re-enabled or re-installed until they're hosted in the Chrome Web Store."

By forcing add-on developers to publish their work in the Store, Google moved another step closer to a "walled-garden" market, the kind popularized by Apple's mobile app ecosystem. That allows Google to vet the extensions and yank those that turn out to be malicious or do something without user approval, like access other parts of the PC or mine personal information.

In February, Google extended the deadline for the Chrome Web Store-only requirement to at least May 1, saying developers needed more time to move their add-ons to the market.

Businesses can hide their extensions on the store from the public at large -- or continue to use group policies to offer the add-ons to their workforce from their own servers -- and developers will still be able to initiate "in-line" installs from their website, assuming the add-on is also in the Chrome Web Store.

But users continued to gripe about the new policy. On a Chrome support forum, some who saw add-ons vanish went into rage mode.