Variables and Types

A value is one of the basic things a program works with — a number, a piece of text, a true/false flag. Every value belongs to a type. Python can tell you the type of any value:

>>> type(42)
<class 'int'>
>>> type(3.14)
<class 'float'>
>>> type('Aria')
<class 'str'>
>>> type(True)
<class 'bool'>

Variables

A variable is a name that refers to a value. An assignment statement creates a variable and gives it a value:

score = 0
player_name = "Aria"
player_speed = 5.5
is_alive = True

Python infers the type from the value on the right-hand side — you never declare types explicitly.

Variable names can contain letters, numbers, and underscores, but must not start with a number. Names are case-sensitive: Health and health are different variables. By convention, use lowercase with underscores (player_speed, not PlayerSpeed).

Keywords — words Python reserves for its own use — are illegal as variable names. These include if, for, while, class, def, return, True, False, and None. Attempting to use one gives a SyntaxError.

Choose mnemonic variable names that tell the reader what the variable represents. Compare:

# hard to read
x1q3 = 35.0
x2q3 = 12.5
x3q3 = x1q3 * x2q3

# immediately clear
hours = 35.0
rate  = 12.5
pay   = hours * rate

Both programs do exactly the same thing. Good names make the intent obvious without a comment.

Numbers

Python has two numeric types used constantly in game math:

• int — whole numbers (health points, lives, level number)

• float — decimal numbers (position, speed, elapsed time)

health      = 100       # int
player_speed = 4.75     # float
gravity      = -9.8

Arithmetic operators: + - * / ** (exponentiation) // (floor division) % (modulus/remainder).

Python follows standard precedence rules (PEMDAS): parentheses first, then exponentiation, then multiplication/division, then addition/subtraction. When in doubt, add parentheses.

// and % are especially useful in games:

tile_col = player_x // 32      # which 32-pixel tile column?
is_even_wave = wave_number % 2 == 0   # every second wave is a boss wave

Strings

Strings store text. Use them for player names, dialog lines, and asset file paths.

level_name = "The Haunted Swamp"
model_path = "models/player/hero"

The + operator concatenates (joins) strings end to end — it is not addition:

greeting = "Welcome back, " + player_name + "!"

f-strings (formatted string literals) embed values directly, which is cleaner for building HUD text or log messages:

hud_text = f"HP: {health}/{max_health}  Score: {score}"

Booleans

Booleans are either True or False. They drive every decision in game logic:

is_alive    = True
has_key     = False
game_over   = not is_alive

Comparison operators produce booleans:

health_low     = health < 25
at_max_health  = health == max_health   # == not =
door_reachable = distance <= 5.0

A single = is assignment; == is comparison. Confusing them is the most common beginner error.

None

None represents the absence of a value. Use it to mark something that has not been set yet:

current_target = None   # no enemy targeted yet

if current_target is None:
    print("No target selected")

Type Conversion

Python will not automatically mix types in ways that make no sense. Use the built-in conversion functions when you need to change a value’s type:

health_str = str(health)         # int → string, for display
bonus      = int("50")           # string → int, from a config file
ratio      = float(hits) / total # ensure float division

int() truncates floats rather than rounding: int(3.99) is 3.