I just downloaded sim city 4 on my windows 10, the game looks just like my mac version I used to have and runs about the same but I cannot get it to load a full screen on my laptop. I have a 15inch screeen and it only covers about 12 or less. I have gone into the game settings chnaged resolution etc and it does change the resolution but nt the screen size. does any one know what I needd to do to fix this?

My screen is 1920x1080, but this resolution is not in the list inside SimCity 4. I added 1920x1080 as a custom resolution by changing my command line arguments from

-CPUCount:1 -f

to

-CPUCount:1 -f -CustomResolution:enabled -r1920x1080x32

I got these arguments from other threads and websites. (I didn't find them in the readme or manual of SimCity 4.) I use GOG Galaxy to launch SimCity 4, so I changed the command line arguments in the Settings inside GOG Galaxy. (If you launch SimCity 4 from a Windows shortcut, you can right-click the shortcut and edit its properties. The arguments go in the "Target:", after the "...\SimCity 4.exe" part.)

If your screen isn't 1920x1080, then use your screen size. I found my screen size (display resolution) by right-clicking the desktop and entering Display Settings.

Use my guide to get the game running using DxWnd.
DxWnd has a built-in framerate limiter that will mostly fix the main problem. And if you want you can follow the extra steps to make the UI/fonts look bigger on the screen.
On DxWnd there's an option to force the game to run in Fullscreen as well (you just gotta know how to read and wonderful things happen in your life LOL )

https://www.gog.com/forum/simcity_series/fixed_these_problems_using_dxwnd_map_scrolling_speed_high_cpu_usage_small_textui/page1