C++ Game: Segfault

C++ game for people who have never written a line of code. You never type. You tap one real C++ line at a time and watch it run.

HOW IT PLAYS
Every card shows a box holding a value, and a bubble with the number that box needs. Below it are two or three big code tiles. Tap the one line that makes the box match. The value flies into the box, and the line you just ran appears under it. Tap the wrong one and it costs a life. You have three lives per drop.

Your first match is guided. @main taps the first card for you, then hands it over.

One new idea per drop, said in a few plain words. When a drop ends, you see the short program you wrote, line by line, and what it printed.

WHAT YOU LEARN
Hall 1: putting a number in a box, changing it, and doing maths with + - * /
Hall 2: int, cout and cin, writing lines in order, and swapping two boxes
Hall 3: if and else
Hall 4: loops
Hall 5: functions
Hall 6: arrays
Hall 7: a box that holds a word
Hall 8: a word made of letters
Hall 9: what is left over, with %
Hall 10: checking if two values match, with == and !=
Hall 11: joining checks, with && and ||

That is 11 halls, 66 drops and 342 cards, and every hall ends with a boss drop: one whole program to finish.

EVERY LINE IS REAL
Each line in the game is ordinary C++. Before it ships, every line is compiled and run with a real C++ compiler, and the value the game shows is the value the program actually produced. If you want to learn C++ and have found textbooks hard to start with, this lets you watch what each line does before you ever have to write one.

MORE TO PLAY
BATTLE: a 60-second race against @nullptr.
A daily card with small tasks, and a streak.
A notebook with one page per hall you clear.
A shop where points buy new profile faces and card colours. Points cannot be bought with money, and nothing in the shop makes the game easier.
Share the first program you finished as a picture, if you want to.

FREE AND PRO
Halls 1 to 4 are free, with no time limit.
Segfault Pro opens hall 5 and up, unlimited practice sets and mock exams, with no ads. Pick monthly, which renews until you cancel in Google Play (Play Store > Payments & subscriptions > Subscriptions), or a 3-month pass, paid once, that does not renew. Google Play shows the price in your currency before you pay.
If Pro ends, you keep your progress in halls 1 to 4, your points, stars and everything you bought with points.

PRIVATE BY DESIGN
Ads are optional videos you choose to watch for a bonus. Pro has no ads. No email, no password, no sign-in. Every hall plays offline.
Your game is backed up under a 12-character code, and that code is the only key to it - keep it and your game comes back on a new phone. Delete the backup any time from the gear menu.
Class rooms are optional: make or join one with a room code, and classmates in that room see the nickname you chose and how many lines you have run. Nothing else, and never your name or your email.
Privacy policy: https://botsquash.com/segfault-privacy

Recent changes:
Smoother rewards: watch a short ad to keep going, double your points or save your streak.
Bug fixes and polish.