The Internet Archive has been on a roll lately, bringing back classic MS-DOS games, Windows 3.1 software, and even defanged versions of old PC viruses.

Now, the site has hit a milestone with its Apple II collection: A group of anonymous hackers have successfully broken the elaborate copy-protection schemes on more than 500 classic games and programs. The result is that these Apple II classics are now playable directly in modern web browsers.

It’s worth noting that Archive.org’s Apple II collection already spanned thousands of titles—yes, including Number Munchers—before hitting this milestone. But as archivist Jason Scott explains in a blog post, a subset of these programs have proven particularly troublesome to preserve in their original form.

“Off the shelf, the programs would include copy protection routines that went so far as to modify the performance of the floppy drive, or force the Apple II’s operating system to rewrite itself to behave in strange ways,” Scott wrote.

The difficulty of cracking these schemes meant that hackers would sometimes omit parts of the code, or embed “crack screens” or alternate color schemes as a way of putting a personal stamp their work. They also tended to focus entirely on popular arcade games rather than obscure software.

Archive.org’s “4am collection” (4am being a term for anonymous persons) attempts to preserve a wide swath of Apple II software in its original form. The site then uses its JavaScript-based emulator to run these games and programs directly in the browser. Each of these offerings include elaborate descriptions from the hackers on how they overcame the disk’s copy protection. (Here’s an example.)

To play the games, you need a modern browser such as Firefox or Chrome, with JavaScript enabled. Most games are playable with a keyboard, though it may take some experimentation to figure out the key mappings.

Why this matters: As with the Internet Archive’s DOS and Windows libraries, the Apple II catalog includes popular fare like Pac-Man and Arkanoid, but also plenty of titles so obscure that they’d surely be lost without efforts to run them on modern hardware. The anonymous hackers behind the 4am Collection are doing important work, even if it wades into legally murky territory.

This story, "Internet Archive brings hundreds of classic Apple II games to your web browser" was originally published by PCWorld .