Game:  Dungeon Siege
Runs on Windows 10:  With No Modifications
Notes:  Does not include Legends of Aranna

This is for the Steam version of Dungeon Siege but is applicable if you know how to add launch options to your particular launcher.

Right click on the Dungeon Siege game name in the Steam library and choose Properties.

From the window which appears, click the Set Launch Options button.

In the screen which appears enter the following text:

width=1920 height=1080 fullscreen=true vsync=false maxfps=60 nointro=true bltonly=true

width=1920 sets the width of the game screen; replace 1920 with your desired width.

height=1080 sets the height of the game screen; replace 1080 with your desired width.

fullscreen=true turns on full screen mode.

vsync=false turns off vertical syncing.  This can help with FPS flutters.

maxfps=60 sets a maximum number of frames per second.

nointro=true turns off the introductory video screens.

bltonly=true turns on BLT mode instead of flip.  (See DirectX documentation for further details.)  Specifically, this handles a situation where nVidia cards flash.

zonematch=true (see screenshot) will, by default, open the multiplayer menu for you to connect.

Although Dungeon Siege was considered highly moddable at the time, it doesn’t appear that any high definition graphics packs were created or survived.

When you start the game you’ll get an error message about the resolution not matching the hardware configuration.  Ignore it.

Once you’re in game you want to hit Escape, then Options.  Turn on All Complex shadows and set Texture Filtering to Trilinear.  Next, crank up the Object Detail as far as it’ll go.

This video represents all of these settings.