The story about Sabina going inside a video game to rescue her son is probably too thin to be an interesting story to write, but it could be a fun game.

It would be a really simple turn-based strategy game, sorta like Fire Emblem without all the RPG elements (or maybe like Wargroove without recruitment?) You'd go through the game and find kids who've been turned into monsters, and you'd recruit them to fight with you. If a character dies, you can't use them for the rest of the battle, but it doesn't affect any future battles.

Each character would have an attack type (strength, blade, or magic) and a set of defensive strengths and weaknesses:

• Sabina (dragon) - Attack type: Strength - Defense: Strength +2, Blade -1, Magic -1
• Yusei (bee) - Attack type: Blade - Defense: Neutral, but with a higher movement range and lower HP
  
• Paralari (fairy monster) - Attack type: Magic - Defense: Neutral
• Kosuke (robot) - Attack type: Magic - Defense: Blade +1, but with a lower movement range
• Tyler (human) - Attack type: Blade - Defense: Strength -1, Magic +2
  
• Sabina (human) - Attack type: Strength - Defense: Strength -1, Blade -1, Magic +2 (obviously you can't use her and dragon Sabina at the same time)