The full version of Ultima IV for DOS was 'made available for free download' at selected sites by Origin (subsequently purchased by Electronic Arts). However, it remains proprietary and not defined as "freeware" or "public domain" (these downloads can disappear or the priced raised at any time at Electronic Art's option). Several homebrew upgrades exist for this game that add features such as VGA graphics and Midi sound. xu4 can used these upgrades as well, or simply recreated the original DOS experience (or the Amiga experience, for that matter). The xu4 project allows this game to run on Linux, Mac OS 8, Mac OS X, Windows, and other operating systems.
The Ultima series continued to innovate with the release of each game in the series. With the 4th game released for Apple ][ and then ported to IBM-PC, the genre was taken to bran new places. And now, playable on Linux. There is no evil big bad enemy to defeat, and the point of the game is not to take advantage of people to get stuff to go defeat the enemy. Rather, the point of the game is for the main character to become a champion of virtue. The goals are literally honesty, humility, honor, spirituality, valor, justice, compassion, sacrifice, courage, truth, and love. Actions, inactions, even words can have less than apparent unhelpful or helpful consequences. Yes, there are still monsters to fight and treasures to find, but this makes up less than 1/8th of the game and the care and purpose in handling these things is more important than the end result.