I recently bought the PC version and would like all the achievements unlocked as i have already done this twice now, 360 and PS4. Thanks in advance!
There are save-editing tools out there on the Net. Just google it up, and you will find some appropriate resources.
That's a wild guess... But I think it was even possible with Menyoo or some other trainer...? Not 100% sure though.
And welcome to 5 Mods!
This is one of the best save editors I have seen so far. Pretty robust and I believe it should have the achievement-tampering kit too.
A funny bug though - once you use it, your stealth ability will max out. No idea why this happens, but it did for me. Consider it a bonus.