Hi and thanks for the update!

I'm happy you've not stop development considering the almost zero interest and support you've have been given since the v2.0 release (for what I've seen here and on YouTube so far).

Unfortunately I've had not much time to test again all episodes and extra modes since v2.1 but I'd like to give you some additional feedback anyway.
Also, note that the following reported bugs and suggested features are referred to v2.1 and that have not been explicitly mentioned in the v2.12 devlog so some of these could still be valid while other could have been fixed/implemented already.

[ BUGS ]:

1) Save files generated via both default and custom save functions do not retain the difficulty level that was active when said save was done, so that only the last (persistent) difficulty level, selected via the "START" button, is always applied after loading a previous save;

2) Save-slots thumbnails are not generated correctly by saving via typewriters and similar, for reference in safe room - 4th floor Relict bulding - Episode 1:
--> [Save slot generated via default RenPy save function]


--> [Save slot generated using typewriter at same point]


This could indicate that custom save function first moves you automatically to the "Options" screen, like if that screen was part of the game images sequence, and then makes a call to the actual RenPy save function, while it should directly call the default save function at the last viewed game image.

The same behaviour could also be reproduced (in any RenPy game) with the default RenPy save command like this:
-- while in game, right click to automatically moving to the "options" menù / "save" tab;
-- move to the "load" tab;
-- move back to the "save" tab;
-- select a save slot to actually save and check the generated thumnail for said slot.

The side effect is also that, trying loading from said slot, game will bring you to the options menù / save tab again instead of moving you back to the last viewed ingame image;

3) In the following scene:

Ada's figure covers the numeric keypad where the access password has to be input (assuming you've to click on its area to move on), which keypad, when visible, also appears too blurred and not highlighted;

4) Some background music doesn't make a seamingless loop (there could be more than the following reported ones):
-- Episode 1, Chapter 2, Cafe (Safe room) at 4th floor;
-- Episode 1, Chapter 2, during the first fight;
-- Episode 3, Chapter 1, Stage (Safe room);

5) In Episode 3, Chapter 1, after taking the coins in the phone booth, returning to the restaurant and trying using the vending machine, Clare still says she has no coins and, moreover, after completed this episode, the coins counter in the items list showed while trading with the merchant remains at zero;

6) There is an inconsistency in game behaviour when the protagonist enters a room and, once all the available options have been checked, he/she says there is nothing to do in the current room: in some case the room name is removed from the navigation options list after exiting it, while most of the time the room name is still visible after the same condition occur (even if there is no actual need to come back there).
Personal opinion: It would be better if all rooms remains reachable in said condition.
For instance:
--> in Episode 3, Chapter 1, at the Book Store, the handwritten note point out many places to explore in order to proceed with the story; however, after the fake plastic book is taken and Claire says there's nothing to do in that room anymore, going back outside,  said room is removed from the navigation options list and that document cannot be red anymore. Thus each time I forgot where to go next (following that list of places) I'm forced to rolling back until said note image shows up again.
So, since (for now) any founded document cannot be red at any time ingame, like it can be in any classic Biohazard game, if one needs reading a document again it should be allowed to go back where said document was found;

[ NICE TO HAVE FETURES (Personal Option) ]:

1) Only at the very first game start, the language selection option could be prompted just after the intro video, avoiding seeing any text in foreing language before entering the main game menu (also the language selection option could be prompted like this: on top just use the word "language" repeated and translated in each supported language, and below it display a list of buttons each with a national flags and the corresponding language name translated accordingly);

2) [By leaving the current UI/Save mechaninc untouched]:

- 2A) Currently the difficulty level, choosen after clicking the main menù "START" button, persists in each episode unlocked, unless one clicks the "START" button again and chooses a different game mode --> this UI/Save mechanich should be explained somehow;

- 2B) The main menù could show the current difficulty level choosen for all episodes;

3) [Alternative UI/Save mechanic]:

- 3A) Since each episode can be replayed individually, the difficulty-level/game-mode selection could be prompted after choosing each episode instead, thus there shouldn't be a persistent difficulty level for all episodes anymore;

- 3B) Only at the very first game start, disable the "EPISODES" button in the main game menu, leaving the "START" button only, and then, after starting the first episode, since the "START" button isn't necessary to set the difficulty level each time anymore (because of previous point), show the "EPISODES" button and hide the "START" one (and make the "EPISODES" button text as bigger as the "START" one);

- 3C) Adding a standard Biohazard inspired save names pattern under each save slot (including episode, game-mode, chapter/building name and map detailed location, like room name);

- 3D) Graphical refactoring of the save page in the spirit of classical Biohazard titles (BH4 is a nice example); 

4) Implementing a third hard-mode, like a real original mode difficulty, that should -include at least:

- no RenPy default saves;
- no auto-saves;
- no skipping function (more on that in the ranking system suggestions down below);
- no roll-back after choices (including those made in fights) which, remaining enabled, could still be used as a (partial) workaround for the missing save features;
- no puzzle solution help via "character thoughs" option;
- ink-ribbons/cassette-tapes/floppydisks become required items for saving, to be searched in the explored areas;
- persistent ammunitions count determined by the quantity found exploring the areas of a single episode and the amount spent during each fight by the same character in that episode;

- 4A) [ If said hard-mode were implemented as suggested ]:

-- it should be a feature unlockable by completing each episode in classic-mode;

-- some puzzle should be slightly changed to make them solvable without the "character thoughs" option.
For instance, in Episode 2 - Chapter 2 - Lybrary, the password becomes a little complicated to found from the given text written in the open book

without using the "Elza's thoughs" option, because the colors associacion with 3 of the 6 highlighted words is not univocal (considering the available colors):
--- the sea could be either blue or cyan;
--- a lightning could be seen as white or yellow;
--- the word "firmament" could be intended as a starry sky (at night) rather than the sky at day time so it could be either associated with "black" or "blue".
So, try guessing the code, then there are 8 different combinations to input at least, because of those 3 words (2 possible colors for each one) wich again makes the puzzle a little tedious to solve;

5) If you don't like naming each mode directly by its difficulty level, (easy/normal/hard etc..) that difficulty level could be written as a side note near each level option name;

6) Adjusting the maximum reaction time allowed in quick time events with game difficulty level (the higher the lever the lower the max reaction time);

7) Implementing achievements/unlockable features/items based on the difficulty selection;

8) Adding a persisten Item Box accessible in the "extra" menu, displaying all the owned/unlocked items, each with an image and a description;

9) Adding an in-game status menù in the spirit of classic BH games, with at least a map and a browsable list of each document found in current episode;

10) (Already implemented in v2.12): In turn based combat, owned weapons and abilities should have each one a brief description of its peculiarities (like action range, hitting points) to be written in the UI after hovering its thumbnail to help better choosing which item to use;

11) Adding a "factory reset" button in the "options" menu, allowing to start the game from zero, without the need of manually deleting each save directory, which are specifically the "<INSTALL_DIR>/game/saves" folder and the OS-related renpy save directories:
- [ Linux ] --> "/home/<USER_NAME>/.renpy/RELICT-XXXXXXX";
- [ Windows ] --> "C:\\users\<USER_NAME>\%APPDATA%\RenPy\RELICT-XXXXXXXX";
- [ MacOS ] --> "/User/<USERNAME>/Library/RenPy/RELICT-XXXXXXXX";

12) Since the typewriter in the "episodes" tab has interactable keys (very nice touch by the way), it could be added to said typewriter a writing feature to be used to input secret codes, where if you first click any keys or a particular key of current typewriter image, then a keys array of a classical typewriter shows up allowing to write on a sheet of paper.
This at first could even be an unlockable feature working like this:
--> at the very first game start, in said typewriter there are missing keys that have to be found throuthout the game in order to be able to use its keyboard and then, when all missing parts are found, it becomes a functional keybord to be used to input secret codes.

13) A safe-room should be named as such only after the player notices first a typewriter and (eventually) an item-box in there (by clicking the "explore" button already implemented in many room navigation options list).
Initially, said room name could be based on the room function in the context where is located and then, after it's recognized as a safe-room, that new info could be added as an extra label after the original room name.
For instance, in Episode-1 the safe room is a Cafe so it should be named first as "Cafe" and then as "Cafe - saferoom" or "Cafe (saferoom)"); this way it should be easier to move back to safe rooms when there are multiple rooms to choose from in the navigation options;

14) In rooms with only one way access, the entrance/exit door should be indicated consistently, for instance it could be indicated as "EXIT".
For reference, in the following rooms the entrance is named each time differently:
- in Episode 1 - Chapter 2 - Cafe (saferoom) -->  [ BACK ];
- in Episode 2 - Chapter1 - Staff room (saferoom) --> [ DOOR ];
- in Episode 2 - Chapter 1 - Library --> [ EXIT ];

15) Implementing animated character figures in place of still images;

16) In Episode 3, Chapter 1, the sequence of steps required to unlock the Museum entrance door is not clear enough:
Since there's only one option simply named "Open", by selecting it the first 3 times in a row Claire still repeats basically the same sentence so that one would think it's useless to try it again.
In my case I stopped after the second attempt and, after completing all of the other tasks still available in the area, in the first run of that Episode, I was thinking there was some sort of bug preventing the story to go further.
Then I've tryed replaying the episode from the beginning multiple times repeating the same steps and at last I've tried clicking on that door lock multiple times randomly and the game finally had continued.
That action button text should change instead after each interaction inviting the player to click it multiple times, as required, in a sequence like this:
"Open the door" --> "Try open again" --> "Try forcing the door lock" --> "Try breaking the door lock".

That's all for now and thanks again for your time and your work!