I gotta be honest: There is no world where having the Guard mode mechanic included in a Visual Novel is going to be relevant and/or beneficial to the integrity of the game/story/product/whatever. A.
B., my only real humble suggestion would be... scrapping ALL of the minigames. The 'Protect Mona' mini was pretty amusing for about 3 seconds - after that, just a waste of time. They don't add to the gameplay, they forcefully break immersion. If it's going to be a Novel based on time-sensitive events occurring or not, I would lean HEAVILY into that. Various story paths that greatly differ from one another is the bread and butter of VN's as a platform for storytelling.
Also, the Art direction is charming - wouldn't worry too much on that; the graphics are complimentary to the story, not the main attraction. Maybe some tweaks during transitions/assets loading (or not loading *Mona Death event*), and this project could be considered polished.
But, for sure, the minigames/survival loop... man. That's something I'd imagine would be found in some Bonus area, to pay homage to some of the experiences (Galaga ftw) that inspired you to develop the project... not a core gameplay mechanic 😝🩵
Cara, na minha opinião, os minigames são incríveis e trazem uma dinâmica diferente para a gameplay, deixando a experiência mais variada e divertida. Concordo que eles ainda poderiam receber um pouco mais de polimento e apresentar um nível de dificuldade maior, de modo a torná-los mais desafiadores.
Outra ideia interessante seria implementar um sistema de avaliação de desempenho, que levasse em conta o quão bem o jogador se saiu em cada minigame. Dessa forma, dependendo do resultado, seria possível receber pontos extras de relacionamento com a personagem em questão, tornando o desempenho do jogador mais relevante e adicionando um incentivo a mais para dominar cada minigame.