Ok, I got it to work, but, be warned, you said any and all:

1. So, there's no minimize/maximize, even alt+tab or windows+d loses the game's video on OBS. So, start the stream with a black screen before even starting Lords 2? (shrugs)

2. There's no monitor-selection on bootup, so shift+windows+(left arrow key) or shift+windows+(right arrow key) moves the splash window from right to left monitor to right monitor, but to move the game's window after splash, go to Steam's "Big Picture mode," (button is next to minimize on Steam.) Click the gear on the top-right, go to Settings ->Display -> Resolution -> change your PnP computer monitor. (Plug and Play.) It changes your primary monitor when booting.

3. <I'm fudging streaming it right now, but it looks like Windows 10 puts Lords of the Realm 2 in a tiny window, like, 1/10 the size of an HD monitor, and then blows it up to full screen.>

So, I'm doing monitor capture instead of game capture, because I'm getting a black screen (any help on this would be nice.):

a. To compensate, I'm dragging the borders of my desktop in OBS so that my desktop stretches far to the right and bottom beyond the dimensions of my computer screen. Lords II is still showing up taking up less than 1/4 of my computer screen, so I exit, blindly guess an expansion of my desktop beyond the borders of my computer monitor, go back into Lords II, rinse, repeat, at this point a screencap of my desktop inside OBS's window is showing just a few icons.

b. So, there's a black bar taking up the entire 1/3 on the right side of my screen stream, but I got an excellent fullscreen picture to work in a widescreen monitor on Twitch.

c. So, I can't click on the chat window to move between the chat's list of people and typing in chat, unless I alt+tab, which loses the game's video until I'm done alt+tabbing back to Lords II, but, uh, I got it to work.

-walloficecream

Ok, so I figured out how to get Lords of the Realm II into OBS using DOSBOX, and it's a lot easier, because DOSBOX is windowed and LOTR II natively is not. But the version I found on the Internet that works with DOSBOX is the original Lords of the Realm II, and Steam's version is the Siege Pack expansion. So I can't migrate my save from Steam. I was just starting the France portion of the original campaign so if someone has a save file from that part in the original LOTR II, send it my way through personal message.

Legendary bro! i was just dragging the window open until it filed the screen. a LOT of trial and error

TY 4help
is there any way to lower the volume of sound?