The Excelsior Series
These games — Excelsior Phase One and Excelsior Phase Two — are arguably not just inspired by Ultima, but in fact are about as close to graphical clones of the game as it is possible to be without incurring the wrath of a copyright lawyer. The first game has a distinctly Ultima 4 feel to it, graphically speaking, while the second game very obviously draws inspiration from Ultima 6. This is nowhere more apparent, I think, than in the design of the ships in the game.
The producers of the series describe the first Excelsior game, Lysandia, thusly:
In Excelsior Phase One: Lysandia, you take on the role of a “Fixer,” a demi-diety under the employ of the Grand Council of World Watchers – a group of dieties who created and oversee the multiverse. Unbeknownst to the inhabitants of the many worlds of the multiverse, history is predetermined by the Watchers. Occasionally, however, something goes awry and history veers off its planned course. It is the job of the Fixer – donning an appropriate guise – to travel to the world in question and set history back on course.
The second game, Errondor, is described thusly:
In Excelsior Phase Two: Errondor, you reprise your role of a Fixer, a demi-deity under the employ of the Grand Council of World Watchers. It is the Fixer’s job to correct deviations in the pre-ordained history of the multiverse. Following your success in Excelsior Phase One, you have been promoted to the rank of Fixer First Class, whereby you will be assigned more important and complex missions.
Both games should work reasonably well in Windows XP; you may need to run them in some manner of compatibility mode under Windows 7. They are not DOS games, so you’ll have to make use of Wine, Parallels, Boot Camp, or whatever your favourite solution for running Windows on a non-Windows system is in order to check them out: hit up the 11th Dimension download page or the freshly minted project entry at the Inspired Works subdomain.