Internet Archive just added over 2,000 MS-DOS games including classics such as The Oregon Trail, Mega ManAladdin, The Lion King, Metal Gear, Wolfenstein 3D, Prince of Persia, Street Fighter, Ms. Pac-Man, and many more, all playable directly from your browser for free.

According to Internet Archive's software curator Jason Scott, the website is using an EM-DOSBOX emulator to make booting and playing the game in-browser possible, but warns that the service is still in beta and may still be buggy. The website's FAQ entry recommends Firefox or Chrome for best performance, but other browsers like Internet Explorer and Safari should work as well. Further improvements to the service have been promised.

As for the legality of the move, Internet Archive has typically taken a stance of uploading everything it can, regardless of legality, then taking down any content when requested without too much hassle. The website's Terms of Use warn that some of the content on the site will be at the mercy of the law and any use is at your own risk:

Some of the content available through the Archive may be governed by local, national, and/or international laws and regulations, and your use of such content is solely at your own risk. You agree to abide by all applicable laws and regulations, including intellectual property laws, in connection with your use of the Archive. In particular, you certify that your use of any part of the Archive’s Collections will be limited to noninfringing or fair use under copyright law.