Mortal Shell: Enhanced Edition

This was one of my last achievement in the game, as there isnt really a reason to spend 50.000 in the store, so I still had plenty of tar left to get.

I found this method to get the achievement without grinding tons of tar:

In the main menu you can see a promt to press to restore saves.
When you go there you will see, that there is your "current save" time and a "last backup" time for your save slots.
Your save slots are backuped at certain time intervalls.
(Unfortunately I couldn't figure out what causes the backup or how to trigger it, but just by loading the save and waiting a bit, it will eventually happen)

You can use this for this achievement, as the tar achievement counter is cumulative, even over different savefiles.

Grind tar and/or use all your items for tar (the more you have, the fewer you have to do this, personally I used around 5k) and once you have a decent amount on you, wait until you get a backup.

Once your current save with all the tar is backuped, you can go to the store and spend all the tar.
Now back out to the menu, restore the backup so that you have all your tar again.
Load the save and you can spend it again.

Rinse and repeat until the achievement pops.