Free software that automatically takes a screenshot every time you click somewhere with your mouse? You’re in luck, there’s one built into Windows 7 and later. Or there was until the Windows 10 Creators Update, when it was bjorked.
In Windows 7 it was called Problem Steps Recorder (PSR), later just Steps Recorder, and can be found via typing psr or steps into the Start menu search-box. It automatically makes one whole-screen screenshot per user click, but is limited in the number of screenshots it can make. It’s meant to be a quick tool that helps IT technicians see what a user is getting hung up on, without having to record and send video or launch a Remote Desktop connection.
Slightly more advanced is the Windows freeware Imago Recorder 1.2, which has no cap on the number of screenshots. You do need to manually hack its config file to get full-size screenshots (open imago.conf.xml and change resize to 0). Automatically captures the whole screen only. Although I’m guessing it may be able to capture a region if you delve into hacking the .XML config further?
The freeware Snappy can capture the whole screen on a click, and is a bit more friendly and fully-featured than Imago. I had no success with getting it to repeatedly capture a pre-defined region on a click, only the whole screen. Though it can grab a region in the usual way.
StepsToReproduce 1.0 was freeware meant as a taster for the more fully featured and paid StepShot, later StepShot Guides. StepShot was bought out for the underlying technology in 2019 and since 2020 is no longer available for purchase. However this cut-down freeware still works, and is a rarity in freeware in that it can do more than full-screen… but it appears to be limited to 800 x 600px in its region capture. The cursor being captured was a feature that could not be turned off, as StepShot was meant to be for rapidly producing software how-to documentation. But if you need the cursor gone, then try a temporary ‘one dot’ or thin ‘bar’ cursor that won’t be noticed. The full StepShot could automatically capture a custom region of unlimited size, simultaneously with user mouse clicks (or a looping JitBit macro emulating the same).
Beyond that you start to quickly get into expensive/subscription corporate territory.
Those who have lots of full-screen screenshots would then need to crop their repeating target-region from each one, by using a friendly freeware batch image-cropper such as Image Tools.