Lesson 4 of 64

Counting on You

What you'll learn:

Store numbers in variables and update them with arithmetic.
Track scores, lives, and other game stats over time.
Use string variables to remember player names or messages.

6% Complete

Lesson 4 – Counting on You

Every game tracks something: score, lives, fuel, gold pieces, goat encounters. Variables are the boxes where you stash those numbers (and strings) so the computer remembers them between lines. Time to start keeping score like a 1984 arcade machine.

[📷 suggested: screenshot of a simple scoreboard showing NAME and SCORE]

The One-Minute Tour

Variables are names that hold values—numbers or strings.
Assign with =: SCORE = 0, NAME$ = "SAM".
Update by reading the current value: SCORE = SCORE + 10.
Numbers use plain names (TOTAL), strings end with $ (NAME$).

Example Program

NEW
10 PRINT "WELCOME, PILOT"
20 INPUT "WHAT IS YOUR NAME"; NAME$
30 SCORE = 0
40 PRINT "HELLO "; NAME$; "!"
50 SCORE = SCORE + 10
60 PRINT "YOUR SCORE IS "; SCORE

Sample output:

WELCOME, PILOT
WHAT IS YOUR NAME?SAM
HELLO SAM!
YOUR SCORE IS 10
READY.

Line 20 stores the player’s name in NAME$.
Line 30 starts SCORE at zero.
Line 50 adds 10 more points by reading the old value and writing it back.

Tip: BASIC automatically treats new variable names as zero (or empty). Explicitly setting them, like SCORE = 0, keeps your intent clear.

Experiment Section

Start SCORE at 100 instead of 0 and watch the totals shift.
Add a penalty: SCORE = SCORE - 5 before line 60.
Print a bonus message when the score reaches 50: IF SCORE >= 50 THEN PRINT "LEVEL UP!".
Introduce lives: LIVES = 3 and LIVES = LIVES - 1 after a “danger” message.
Mix in another player by adding INPUT "RIVAL"; RIVAL$ and tracking two scores side-by-side.

[🎥 suggested: clip showing score increments and a bonus message appearing]

Concept Expansion

Variables remember state so your program doesn’t have to start from scratch each line. Later you’ll use arrays (DIM) to store groups of related values and DATA statements to preload level layouts. Assembly lessons connect this idea to actual memory addresses—today we’re enjoying BASIC’s friendlier labels.

Game Integration

Scoreboard: SCORE = SCORE + POINTS every time the player succeeds.
Lives: IF HIT THEN LIVES = LIVES - 1 and IF LIVES = 0 THEN GOTO GAME_OVER.
Timers: TICKS = TICKS + 1 inside your main loop, paired with IF TICKS = 60 for once-a-second events.
Inventory: HAS_KEY = 1 to unlock doors later in the adventure.

From the Vault

Commodore 64 — revisit how the interpreter stores variable tables in memory so your score persists between lines.

Quick Reference

REM Variable essentials
SCORE = 0
LIVES = 3
NAME$ = "ARTHUR"
SCORE = SCORE + 10
IF LIVES <= 0 THEN PRINT "GAME OVER"

Numeric variables hold whole numbers or decimals (BASIC stores them as floating-point).
String variables must end with $.
Spaces are optional: SCORE=SCORE+1 works, but spacing improves readability.
Variables keep their values until you change them or type RUN again (which clears memory).

What You’ve Learnt

Variables act as named storage boxes so programs can remember state.
Updating a variable reads the current value before writing the new one.
Numbers and strings live in different namespaces (SCORE vs SCORE$).
You can already build scoreboards, life counters, and basic inventories.

Next lesson: Random Encounters — unleash RND to add surprises and procedural twists.