If you're looking for geometry learning, try to make an asteroids-like game.
It's not too challenging as to turn someone down, but lots of fun and you'll learn how to apply geometry. Specially sine and cossine, which my teachers did a terrible job in teaching what that was all about (only teached transformation formulae, never applying them). I only learnt what it was meant to do when I tried to do a subspace-like game.
Nice... Keep thinking that you're safe, and I won't tell you how I would have gotten a virus just today when I downloaded a basic app for my HP calculator, were it not for my AV software, which detected it just when I downloaded the installer from HP's official site.
I hope you never download anything from anywhere, including sites which should be safe and trustful, but just aren't.
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