Ultima
Ultima was one of the first computer game series my brother and I played. We started on Ultima II on the commodore 64. After getting an Apple IIC we played Ultima IV and V on it. We seemed to have skipped Ultima III until it was on the NES. I have fond memories of the maps for Ultima III though V. I didn't care much for Ultima II's maps (it's more or less the Earth in various ages). I never played Ultima I but the map looks intriguing enough.
Ultima VI and onwards the maps does not have the same level of abstraction as the earlier titles so I don't feel like I could map them appropriately using the available extracts. Since Ultime VI, VII and IX and all based upon Britannia the maps for IV and V should suffice. For Ultima VII 2 the map of the Lands of Despair and Danger from Ultima 1 should be a pretty close fit except for the northern part of the isle not being a cold climate.
The tile maps on each page were created from a program called Ulimatrix (V0.29). It's an old program (from 2001) that I had archived on my PC. I was kind of surprised it still ran.
Ultima maps I have converted to hexGimp have a constant of towns being on grasslands, dungeons in mountains and signs. In my conversion I tried to align the towns and dungeons as best fit as I could manage. I removed the the signs as I didn't think they warranted a whole hex..
During the course of my map conversions I was able to recreate a the sprites used for towns and other overlay items from Ultima V and add them into hexGimp. As for terrain I tried to match the best per the information available via the manuals and documentation at the Ultima Codex Terrain page. For Ultima III I used Broadleaf Savannah for the brush lands. For Ultima IV/V I used shrublands. I chose to change the "brush" between II and IV/V as I wanted to see a which looked better for the terrain on the map. For Ultima V's underworld I used a new hex I made for Underdark wetlands - undeground fungal wetland.
Ultima I - Ancient Sosaria
I never played Ultima one but wanted to create a hex gimp of it's continents. I think the scale for these maps should be 24 miles per hex given their small size and are supposed to be continents. Another take on these lands could be various demiplane "echoes" of each other. Each continent resembles the other continent next to it, either rotated, flipped and additional water added.
Ultima III - Sosaria
Ultima 3 was another of the RPGs that made a n impression upon me. The maps below are derived from the PC version of the game, but I mostly played this game on the NES. From a DND persepective the map for Sosaria feels like a demi-plane. Though with some customization (removing the parts of the isle that is on the corners) it could be a decent isle. Given the small size I think it would be 24 MPH at a minimum. At some point I'd like to make a larger version of the map as an isle and a setting for a campaign.
Ambrosia is kind of a not as useful for a world map. It's more like a large scale dungeon.
Ultima IV & V - Britannia
This is one of my favorite maps. It's got a decent size and varied terrains. I used the shrublands terrains to represent the brush terrain. Were I to use it in my own campaign I might swap it out to be Oak Savannah as it would look better and make more sense.
The difference between Ultima IV and V are a couple of islands added in Ultima V and the addition of a desert in the north eastern part of the continent. I think the desert is a little over done, but if tied to some kind of magical drain on the land it makes sense. I might combine Ultima IV and V to make a desert with an Oasis in the middle.
Rivers on this map are odd... I think they'd need to be redrawn.
Ultima V - Underworld
I remember exploring these under ground areas for hours as a child. I like what was done for the maps, but as I've aged I realized the maps wouldn't make the best underdark as each of the sections of the underworld are meant to be separate instances with specific objectives.