When I try to start a new game I only see a square section in the top left corner, the rest of the screen is black. Any Idea how to fix this?

Is this the Software or D3D version?

Edit: Wait, which game is this for, anyway?

Populous: the Beginning haha, sorry I didn't realize all the Populous games were in the same forum. I installed the Multiverse Launcher and it works now, the planets on the map screen look kind of weird but other than that it works fine now. =D

Well, it's a 20 something year old game relying on now nonexistent tech.

I see this is a very old question, but I have a simple fix.
The shortcut that is created by the GOG installer is trying to run the Direct3D version of the game. This fails on Windows 10, probably as that API has been altered a lot in the last 20 odd years.

However if you go to the intsallation folder for the game you will see four executables, two have names starting with D3D and two that don't. (ie: D3DpopTB.exe, D3DpopTBUW.exe and popTB.exe, popTBUW.exe)

Simply changing the shortcut (or create new ones) to run the non-D3D versions makes it run with sodtware rendering. As the resolutions and the lever of details are very low by todays standerds, any modern CPU can run this with ease.

Also: This is how you find and run the Undiscovered Worlds.

NOTE: There is a lot of screen flashing (showing the desktop and back to game) as the game starts and switches between load screens, intro videos and the game itself.

Thanks for the advice! :D