If you didn't keep track of your layer switching on each level right from the start, and as the game doesn't tell if you've used it or not on specific levels, there's currently only one way to find out which levels you've finished without switching to individual layers; that is, by checking your savefile on the Registry Editor.

This guide uses Windows's Registry Editor, an OS built-in tool that stores important values to the correct functioning of the operational system and of software installed. If used incorrectly, it may bring DOOM UPON YOUR COMPUTERRR!

There's not that much danger involved, as we won't be altering any values, just checking some out... but be careful anyway, and proceed at your own risk.

Firstly, open up the Registry Editor by pressing Win+R and typing in regedit, then navigate to this key:


This is what we'll be working with:

The value strings related to the levels follow this pattern:

The numbers at the end don't matter to us.

The x equals to the number of a level's corresponding file, not the level itself. In regard to the Unity Engine and its numbered system for level files, in this case inside Circuits's folder, the level file with a number x will actually correspond to the level numbered x+1 (e.g. file named "level 4" corresponds to level 5). As the game's saving system (located on the Windows registry) also follows this system, strings starting with LEVEL_0 correspond to the ones of Level 1, and LEVEL_1 → Level 2, and so on. You may even notice that there are no strings starting with "LEVEL_25" (the last level of the game), as those start with "LEVEL_24".

The [stat]s are as following:


And the ILU strings are what matter to us. Search for those with the value of 1, add one to the string's level number and replay the corresponding level. Mind that clicking the white layer doesn't count as changing layers (I'm looking at you, Level 3).

Unlike the game's achievements, these stats are updated as soon as you finish a level - there's no need to exit the game to update them (simply press F5 on regedit).

- LEVEL_6_ILU_h3780700501: This string stores if you've completed the Level 7 without switching to a single layer. You want this to be off (value = 0);
- LEVEL_10_PERFECT_h44884097: Will be on (value = 1) if you've finished the Level 11 with only one check (never gotten the "Something is wrong" message at the end);
- LEVEL_24_STATE_h168300834: Completed Level 25.

By finishing all the levels, except for the Level 3 (even if possible), without switching between sound layers, you will unlock the Golden Ear achievement! And now that you've probably read all of that, let us wait for the developer to add a feature to display this in-game, thus basically nullifying this whole guide.

There we go. If this guide has helped you out, don't forget to rate it. And if there is any way that I can make it clearer, do comment.