On some systems (not mine), GTA2 refuses to run at 1024×768 or any resolution higher than 640×480, even if you select a higher resolution in GTA2 Manager. siwuzzz at gmail has created a patch to work around this problem. The patch is for the free (9.6F) GTA2 exe file. You don’t actually see more in higher resolutions since GTA2 just stretches the image. The only reasons I can think of for not using 640×480 is if you were running in a window (needs desktop set to 16bit colour) or using a strange monitor that doesn’t support 640×480.
On my systems, this had a strange side effect of making the menus only use the top left 640×480 of a fullscreen 1024×768 window. I don’t recommend using it if GTA2 already displays fine for you.
Changes a byte at location 0xCB2C9 from 74 to EB.