I'm extremely happy that you're enjoying the game, and am completely blown away that you're making a walkthrough as well. I honestly never thought this game would be noticed enough for that. Thank you so much!

I certainly see potential in this. If you were to take it further, perhaps some way of marking which cubes were mines, and also perhaps modifying it so that cubes don't count themselves in the mine count. beyond that, loving it!

Having a save file in plaintext is a bad idea, because it can be easily edited. You should encrypt it.

being able to change a letter by putting another one over it is useful if you make a mistake, but if you've got a word in place and try to extend it only to realise you're not allowed the resulting word is a game breaker, as there's very little you can do to fix it

Glad to know you're enjoying the game! It's worth mentioning that there is very little linear progression, and some puzzles you can access earlier can only be solved with information from later ones.

thank you very much for the kind comments, and I'm super happy that you enjoy it!