Lock-on aiming in possible in GTA SA on pc. Pause the game, go to options, choose controller options, you'll see the configuration. Change it from mouse+keys to joypad (remember that ps2 uses a joypad in laying its controls). You can still use everything but the mouse for camera controls. Turning the camera is placed on the NUM controls 2,4,6,8

Yup. I try to move my mouse around, but it has no effect. What do I do? I also have this problem for GTA: VC.

So what I'm saying is that the rest of the game runs smoothly, except for the mouse. When I move the mouse it does something like stuttering, and I can't aim properly (hence the "mouse lag", even sometimes CJ keeps walking even though I'm not pressing anything cuz somehow it tries to catch up in the game
Thanks, Jamal! Indeed, the issue with San Andreas was in CPU affinity, and moreover setting affinity on the launch (eg. using "start /affinity 1 gta-sa.exe") doesn't work - it explicitly has to be set when the process is already running. I'm fed up with all the task manager clicking, so I made a short powershell script. Ie.
DOWNLOAD for GTA San Andreas. DOWNLOAD for GTA Vice City DOWNLOAD for GTA III Usage The changes take effect automatically, no need to toggle anything when the game is launched. Supported games GTA III 1.0 (all versions) GTA III 1.1 (all versions, including Steam and Rockstar Games Launcher versions) GTA VC 1.0 (all versions)
The problem I had (and assume he has the same or similar) is that when you move the mouse the camera does not move at all in game. For me, I could move the cursor in the pause menu but clicking did not respond. The fix I suggested is not a mod. It does not allow you to move the camera in car, it just gets the game to recognize the mouse. uGTP. 405 417 166 237 117 276 84 132 64

gta san andreas mouse not moving camera