Growing Sequences

Until now the sequence has been hardcoded — “132” every time. Memorise it once and you win forever. A real memory game does not let you off that easily. Each round, a random colour is added to the end of the sequence. Round 1: one flash. Round 5: five flashes, all from memory. The string grows until the player’s memory gives out.

Growing the String

Replace the fixed LET s$="132" with this line at the start of each round:

  82 LET s$=s$+STR$ (INT (RND*4)+1)

s$=s$+STR$(INT(RND*4)+1) does three things in one expression:

• INT(RND*4)+1 picks a random number from 1 to 4 — one of the four panel colours.
• STR$(...) converts that number to a string character.
• s$=s$+... appends the new character to the end of the existing sequence.

If s$ is "13" and the random number is 4, then s$ becomes "134". Each round, the string grows by one character. Round 1 has one colour. Round 5 has five. Round 10 has ten.

The Game Loop

Initialise the sequence as empty (LET s$="") and the score as zero (LET sc=0) before the first round. The flow becomes:

1. Append a random colour to the sequence string.
2. Play the whole sequence (FOR/NEXT through the string).
3. Player repeats the whole sequence.
4. If correct — increment score, display “Correct!”, GO TO step 1.
5. If wrong — game over.

GO TO at the end of a successful round sends the program back to step 1. The sequence string is the entire game state — one variable holds everything the game needs to remember.

Score Tracking

LET sc=sc+1 after each completed round. Display the score on the header bar with PRINT AT 0,26; PAPER 1; INK 6;"Sc: ";sc. The score updates at the start of each round so the player always knows where they stand.

String Concatenation

s$=s$+"4" joins two strings into one. The original string stays intact and the new character goes on the end. This is called concatenation — gluing strings together. It is the same operation in most programming languages, though the symbol varies (some use . or & instead of +).

Try This

• Play a few rounds. How far can you get before your memory fails?
• Add PRINT AT 19,1;s$ to display the sequence on screen during testing. Remove it when you are done — seeing the answer ruins the game.

What You’ve Learnt

• String concatenation — s$=s$+"4" appends a character to the end of a string
• STR$ with RND — STR$(INT(RND*4)+1) produces a random digit character “1” to “4”
• Growing state — the sequence string gets longer each round; the game gets harder
• GO TO as game loop — jumping back to the start of the round creates an endless game that only stops on failure
• Score tracking — LET sc=sc+1 counts completed rounds