Ever stumbled across one of those weird, hyper-specific Japanese educational games? Sansuu 2 Nen - Keisan Game is exactly that—a math drill disguised as an NES game. It’s for second-graders, but don’t let that fool you; some of these problems get sneaky fast.

You’ve got simple addition and subtraction at first, then suddenly it’s throwing three-digit numbers or quick-fire questions at you. The pixelated graphics are pure 8-bit charm, with little number sprites bouncing around. No fancy RPG mechanics or power-ups here—just you, a timer, and your ability to not embarrass yourself in front of a 1980s Japanese classroom.

Perfect if you want to test your mental math or just enjoy retro oddities. Just don’t expect any mercy when the clock’s ticking.