I put together a video explaining the route I used in my run of Ultima VII, which you can watch here:

Honestly, the trickiest bit of this speedrun is getting DosBox set up for this game. Ultima VII uses a custom memory manager that doesn't play well with others and back in the early 90s when I was first playing this game it was a pain to get to work on most PCs. The main settings you will have to change from a vanilla DosBox 0.74 installation are as follows:

cycles=12000 joysticktype=none ems=false umb=false

I would not run the game without sound, however, since even though you get better load times with no sound, the Guardian's taunts when you are in the Blacksmith's shop and when you are stealing the chest for the stairs cause the game to pause and you have to click through his dialogue on screen which slows things down.

Time starts when you gain control of the Avatar during the opening cutscene. On my system, with Roland MT-32 emulation, there was about a 28.30 second delay between pressing Journey Onward and the mouse icon showing up.

Once you start a new game the first thing you will need to do when you gain control of the Avatar is head down and to the right. This is to avoid an additional bit of forced dialogue with the mayor of Trinsic.

Once you dodge the mayor, you can proceed to the burned out blacksmith's shop in the southern end of town. Just to the east of this blacksmith shop (near the southern exit to Trinsic) are two houses. In these houses are 3 crates and a chest we need in order to build a staircase. collect these crates and the crates in the blacksmith's shop and build a set of stairs leading onto the roof of the building. Once on the roof, you just walk into the western side of the chimney and you are teleported into the Debug Room.

Once in the Debug Room, flip the switch on the wall, grab the invisible crate in the top left corner of the room, and put on an invisibility ring from one of the 8 chests on the floor. Then walk onto the teleportation pad in the center of the room.

In the next room, there are several teleporters. The one you want is in the northern part of the teleporter rooms. It is the bottom right teleportrer with the pile of bones. This takes you to the titular Black Gate. Once there you simply match the prisms in the invisible crate you grabbed with the pedestals and walk into the Black Gate. Thus ends Ultima VII. Congratulations, the world is destroyed.

Time ends when you enter the Black Gate.