@pdotjpg Thank you for the feedback and I'm glad you enjoyed the game! Regarding the timer, it was actually the first mechanic that we came up with as we wanted to make a "bomb defusal game" where you have to solve puzzles to defuse a ticking bomb. It is a bit harsh by design since we wanted players to feel like they overcame a big challenge if they beat the game but we understand that trying over and over again is not enjoyable for everyone.
If we were to expand this game we would definitely consider creating a zen mode and moving timed mode into being its own game mode. That way every player can play the game how they like, just enjoying puzzles or trying to see if they can solve diffucult ones under pressure.
An undo button is a great suggestion and not something we even considered during development.
Again thank you for the great feedback!