Yup, still the same issue.
Then it's not an issue with installable software (ex. game or editor)
It's either OS/Driver or indeed a keylogger as
@lunarlander says.
Although if it's keylogger then it's certainly a bad written one, and since you reinstalled OS,
the only way it could get into your PC again is by installing same set of favorite software again,
such as pirated version of game.
You said keyboard works fine on another PC so it's not keyboard.
You said to have reinstalled OS but there is one obvious discrepancy:
Your OS version 18363 is way out of date which means you do not benefit from latest fixes or improvements.
Currently latest version is 19042 which is 1 year ahead of yours (Windows updates do not count here)
Download Windows 10 (microsoft.com)
I think it's time to back up ALL of your files to external drive and do
clean reinstall:
https://techguy.org/1235557
When you're done, first step is to install
nothing (not even a browser), and do
not use Windows update.
In your fresh system open keyboard properties and try to reproduce problem by typing letters into dialog box shown in my previous post.
Next step is to get MSI drivers from here (Only drivers, not utilities or BIOS files):
SUPPORT FOR Z97 PC MATE
Driver install is done this way:
1. Install chipset driver, restart PC
2. Install the rest of drivers, restart PC
Again test keyboard trough keyboard dialog.
Next step is to install Windows updates,
excluding following:
1. Optional or Preview updates
2. Device drivers
Again test keyboard trough keyboard dialog, if the problem persists, try out other USB ports and keyboards.
Next step is to install your game and check for game updates.
Go ahead and test it.
If this did not solve your problem, create live linux USB, boot from USB, and test your keyboard and mouse.
If the problem is present there as well, it's motherboard, USB port or BIOS issue, otherwise it's an issue with Windows and/or drivers, in which case use Windows updates and install optional and preview updates, as well as any drivers it might offer, then try your tests again.