how to display 4:3 full screen game on widescreen monitor without stretching? I am playing the game Age of Empires 1 on Mac OS Sierra, running on a 11 inch macbook air connected to a 23-inch Acer monitor with native 1920 x 1080 resolution. The game is for Windows and doesn't have an official Mac version, so I am using a program called "Porting Kit" which appears to be some kind of Wrapper utility for Wine.

The game itself is 1024 x 768, so when I run it, my screen goes into full screen mode, but the 4:3 aspect ratio is stretched all over the screen, so the picture is shorter and fatter than it would be. I would very much prefer to play with black bars on the left side of the screen, so that the picture at least displays in the correct aspect ratio, not stretched.

I found some forum threads where PC users with Nvidia cards had this problem, e.g. the thread here. However, my Macbook air, if I'm not mistaken, has Intel integrated video, so that doesn't apply.

Also, I tried changing the settings in the Mac OS display preferences, and hold Alt/Option while clicking "scaled" which gives a list of resolutions, including 1024x768. However, when I switch to that resolution, Mac OS also stretches. This is strange because I've seen screenshots of others' display preferences resolution list, and they have things like "1024 x 768" and "1024 x 768 (stretched)", e.g. two different versions, which implies the first one is "unstretched". However, my resolution list doesn't have the corresponding "stretched" versions, and unmarked one is stretched though. Strange.

I also tried fiddling around with the hardware controls on my monitor (an Acer G236HL), i.e. the physical buttons near the power button on my monitor. There seems to be an option called "Wide Mode", which is set to "Full", but there seems to be no way to change it, although the interface suggests there are other options besides "Full", but trying to change that option results in nothing happening, e.g. there do not appear to be any other options.

How do I force my monitor to display a full-screen 4:3 picture with black bars on the two sides, rather than stretched? Again, the program I am using, "Porting Kit" by some guy named "Paul the Tall", doesn't appear to have any "play in windowed" mode feature. There appears to be a "AOE rise of rome unofficial HD patch" (also installed via Porting kit) made by yet another person that allows windowed mode, as well as widescreen resolution support. (edit update: for some reason, windowed mode using this patch crashes the game for me, but full screen mode works, and it allows playing the game in 1920 x 1080 resolution, so technically this is fine. However, I was wondering if there is a more general solution to this problem that can work for other full-screen 4:3 stretched games)
Right-click the port in your Porting Kit library, press "Wineskin Tools" -> "Launch Wineskin". In the window that opens, press "Screen Options".

Select "Override" instead of "Automatic" in the top, then select "Fullscreen" in the left and choose the "Resolution" that you want to use below.

Also, that port uses Mac Driver, which is incompatible with the configurations above, so uncheck the "Use Mac Driver instead of X11" box. Be warned: the game was tested with Mac Driver and not X11, so it may not work if you disable that box. If it stops working, you can repeat the process and check that box again.