Calculation Castle: Greco's Ghostly Challenge "Subtraction"

About

Calculation Castle turns subtraction drills into a spooky adventure. You solve math problems to unlock doors and defeat ghosts in a castle filled with increasingly tricky challenges. Starting with simple 1-digit equations, the game progresses through 10 stages that teach borrowing techniques and advance up to 4-digit problems. Each cleared room brings you closer to Greco, the mischievous host who throws math-based obstacles in your path. Correct answers let you move forward while incorrect ones send you back to earlier steps. The playful rivalry with Greco and the castle’s eerie atmosphere make learning feel less like homework. Though straightforward in design, the structured difficulty curve has helped some players improve arithmetic speed. Released in 2018 for Nintendo Switch, it’s a niche title for parents seeking educational games or kids who enjoy turning skills into progress. The lack of time pressure or high-stakes failure keeps it approachable for younger audiences.

Storyline

"The name's Greco. I'm sendin' you an invite to face the challenges that await in my castle! So, let's play a game!! I live at the very top of my castle! Do you got what it takes to reach me? It won't be easy. In order to get to me, you gotta pass through several rooms. In these rooms, you'll have to solve subtraction problems to pass. That's why my castle is called the Calculation Castle! Moreover, my castle is full of ghosts with many tricks standing in your way, so good luck and do your best! If you manage to beat my ghostly henchmen and get through the rooms, you'll receive lots of hidden rewards…but can you do it? I guess I'll wait and see! Heh heh heh…"