Firstly, thanks for playing!
Answering your questions: The optimization techniques that I used was making objects that were offscreen invisible. I also made certain animations of objects not play unless they were in camera view. I used Gdevelop to create my game. It wasn't hard to create my game with Gdevelop; actually, creating my game with Gdevelop made the development process much smoother. The only challenge that I faced was a problem with the UI when the game was exported. The UI that I make in the game doesn't exactly match how the UI looks when the game is exported. I had to go back and re-export the game the fix this issue.
The artwork was made using a free pixel art software called Piskel. The game idea and story was inspired by the concept of needing to balance the mind. In real life, if the different aspects of the mind(in the game's case: happiness, pride, peace, and love) are not taken care of, people start to go insane. There is a force in our mind that wants to do good and another that wants to be bad. The evil force has to be fought. The gameplay was created with the idea of multitasking in mind. Just like in the real world, we have to multitask between the different parts of our minds. For example, you may have love in your life, but that doesn't equate to peace and vice versa.
I only intend to develop Out of My Mind as a full game if it wins(1st, 2nd, 3rd, or Hidden Gem). This would show me that this game is an idea that people are interested in and want to see more of. I have already rated your game, but I didn't leave a review(I have a bad habit of not leaving reviews). I will do so before the end of the voting period. Once again, thanks for playing and asking questions.