Railroad Tycoon II screen resolution
Solution 1:
It is an old game, so the resolution and aspect ratio's are a bit dated. The trick is to not pick the highest resolution, but one that has the same aspect ratio as your screen. For example, 800 x 600 has an aspect ratio of 4:3. You probably want something 1280 x 720 for a Full HD (1920 x 1080) screen, because that has the same aspect ratio of 16:9.