Is there a way to check the status of the "All I need is one arm/finger" achivements?

Question

The achievements "All I need is one arm" and "All I need is one finger!" require beating all guardians without using subweapons, in a single save file. As far as I'm aware, there's no way in-game to check if a save file has violated this requirement.

I'm pretty sure I know all of the rules (shields are fine, no other subweapons, no weapon fairies, only ankh bosses and the final boss matter), but it'd be nice to be able to defeat a boss and be certain I didn't accidentally press the wrong button and not realize it or something.

Is there any way to check this, either inside the game or out? I couldn't find any information on cheat engine or save editing that wasn't for just ordinary cheating.

I'm specifically asking for La Mulana 2, but if there's a solution that works for both games that would still be appreciated.

Answer 1

I'm assuming there is no in-game way to check the status of the achievement.

The achievement can be checked by inspecting the save file. The save files are in a binary format with a simplistic XOR encryption, so inspecting them isn't trivial. It will require a hex editor/viewer and a tool for doing XOR. Windows Calculator works if set to "Programmer" mode. "XOR" is available under the "Bitwise" button.

As a disclaimer, I'm confident that this works from my testing, but I have a sample size of 1. I can't guarantee that there aren't other versions of the game with different file offsets. In particular, I don't own the Tower of Oannes DLC. It's possible this changes the size of the file, or which regions of the file are filled with 00 bytes (which are needed for decryption), or anything else.

The saves are located at %APPDATA%\..\LocalLow\NIGORO\LaMulana2\Save. The number of bosses defeated without subweapons is located at position 0x4DBC (Decimal 19900) within each file. This will be 00 for a brand new file, 01 after defeating Fenrir without subweapons, etc.

This value is encrypted. The encryption key changes each time the game is saved. The solution to decrypt is to take the value at position 0xBC (Decimal 188) and XOR it with the value at position 0x4DBC. In all my save files, 0xBC is always 0 after decryption and uses the same XOR key as 0x4DBC.