Ever wanted to know if your brain feels older than you actually are? Dr. Kawashima’s Brain Training on the DS is basically a daily check-up for your gray matter—except way more fun than it sounds. You’ll scribble math problems with the stylus, try not to embarrass yourself at quick counting games, and fumble through memory tests while a little digital Dr. Kawashima judges your performance. (Spoiler: My brain age started at 60. Not great.)

The best part? It actually tricks you into wanting to improve. After a few days, you catch yourself getting faster at those Sudoku-like puzzles or finally nailing the voice-controlled syllable counts. Just don’t be surprised when you start muttering calculations under your breath in public. It’s weirdly satisfying to watch your "brain age" drop after a week of stubbornly refusing to let a DS game outsmart you.

Fair warning: The handwriting recognition can be hilariously bad—prepare to argue with the game when it misreads your perfectly legible "7." Still, it’s a solid way to kill time on the bus while pretending you’re doing something productive.