Right-click the game in your Steam library. Manage > Browse Local Files. Open the bin folder and right-click on the duke3d.exe. Under the Compatibility tab you'll find the "Change high DPI settings" option. Open it, check the high DPI scaling override box and select the Application option from the drop-down menu. Close the windows with OK, boot the game and crank up the resolution. It should actually center properly now. Go say hi to Candy for me.