Save Scum Method has now been patched (26/02/23). I'll leave the video below for anyone who might be curious what that was.Lootyagins are the reward chests found in the 8 Testing Grounds (Bronze, Silver & Gold). Each testing ground has 3 Lootyagins to find making a grand total of 24 to open.
A Testing Ground consists of 2-3 large puzzle rooms, which get progressively harder as you go through them. Upon completing each room you'll be rewarded with a Bronze, Silver and Gold chest (Lootyagin). In some of the Testing Grounds you may encounter a "Combat" room where you need to kill all enemies before moving on.
See my full walkthrough guide below for all 8 Testing Ground locations, entry, puzzles and Lootyagin chests:
Old Method: