(if you already know some programming), I don't think quest has the ability to do:
player.agility += 1
// which is maybe what you were trying to do (if you already know some programming)
so you got to write out the full expression/statement in quest:
player.agility = player.agility OPERATOR Value
// Value: 1, or whatever you want
// OPERATOR: +, or whatever you want (subtraction: -, multiplication: *, quotient division: \, or remainder division: %)
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if you don't know programming, a quick lesson:
programming's Assignment Operator/Operation: =
is not the same as math's Equal Operator/Operation: =
(quest's) Programming's Assigment Operation:
Object_name.Attribute_name = Object_name.Attribute_name + Value_or_Expression
the result of the entire expression (the right side of the '=' symbol) is STORED/ASSIGNED INTO/TO the Attribute VARIABLE (on the left side of the '=' symbol)
whereas, as you know with math:
x = 10
y = x + 5
y = 15
x = 10
5 + x = y
y = 15
but, since when doing programming's assignment operation, for example:
1 + player.strength = player.strength ---> ERROR!
player.strength + 1 = player.strength ---> ERROR!
player.strength = player.strength + 1 ----> NO error
player.strength = 1 + player.strength ----> NO error
conceptual example of how it works:
initial (old) Value (shown as set/assigned to its Attribute VARIABLE): player.strength = 0
statement (Assignment Operation): player.strength = player.strength + 5
// value: 0
// Attribute (VARIABLE): player.strength
// expression (dynamic/variable addition operation): player.strength + 5
old value: player.strength = 0
player.strength (new) = player.strength (old: 0) + 5
player.strength (new) = (0) + 5 = 5
new value: player.strength = 5
old value: player.strength = 5
player.strength (new) = player.strength (old: 5) + 5
player.strength (new) = (5) + 5 = 10
new value: player.strength = 10
old value: player.strength = 10
player.strength (new) = player.strength (old: 10) + 5
player.strength (new) = (10) + 5 = 15
new value: player.strength = 15
old value: player.strength = 15
player.strength (new) = player.strength (old: 15) + 5
player.strength (new) = (15) + 5 = 20
new value: player.strength = 20
you get the idea...
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in quest, this is the terminology:
VARIABLES:
-> Variable // examples: result = Value_or_Expression, handled = Value_or_Expression // Variables are local in scope
-> Attribute // examples: player.strength = 100, game.greeting = "welcome to tron", orc.dead = false, orc.dead = true, HK.awesome = true
-> Parameter // (used with Functions and Commands)
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if you want/need more detail on Attributes (and the If Script):
viewtopic.php?f=18&t=5559if you don't already know this stuff, lol