After analyzing the game files, Steam user Trashes has figured out a solution for Level +15. Here is a guide so you can finally get the last achievement: https://steamcommunity.com/sharedfiles/filedetails/?id=1835222158

If a random puzzle is generated, it's possible for it to already be completed. In order for the game to notice that it's completed, a user has to click a cell to make the solution incorrect, then return it to the correct solution.

As far as I can tell, I've solved level +15, but the game doesn't recognize it as solved. Here is my solution (spoilers): http://steamcommunity.com/sharedfiles/filedetails/?id=1240918402 Can somebody please take a look and tell me where there is a mistake, or if they've had the game recognize a solution to level +15?...

Some stuffs that should be changeable... The volume of the music, it's too loud, we need to go to the Windows to change it. The background changing from bright to dark, this blind me as hell sometimes. An option to mute only the musci / sound effect / both. A tutorial in how to create random levels....

Create a Random Level isn't that hard after you understand what "Candidate" means. Candidate are those numbers inside the cell. When you choose the Min Candidate and the Max Candidade you will choose how much candidates a cell will have. That means you n...