TaaZ's ITEM SYSTEM
Well, I know some of you have been looking for a decent item system that lets people only use one weapon at a time or one armor, or whatever, so this tutorial was produced from being bored.
This tut might give you beginners more knowledge with triggers and/or variables.
What you need:
- A. Basic Knowledge of the Object Editor
B. Basic Knowledge of Variables
C. Basic Knowledge of the Trigger Editor
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First and foremost, we are going to start with a few variables...
If you are going to have 5 players in your map that cant pick up two weapons
(I'll be using weapons as an example) then you need 5 variables.
I named my variables
- Only1Weapon1
Only1Weapon2
Only1Weapon3
Only1Weapon4
Only1Weapon5
The numbers at the end represents the player number, ex. player 1 red = 1
These variables need to be boolean and false as default
Lets get started on the triggers...
Make a trigger called
"Only1Weapon1"
And another trigger called
"Able2PickUpAfterDrop1"
NOTE: these triggers will be for player 1 red
Go into the trigger Only1Weapon1 and create a new Event:

Unit - A unit owned by Player 1 (Red) Acquires an item
Simple Event, no need to explain it.
Now create a few Actions, this is what it should look like after I explain some of it:

If (All Conditions are True) then do (Then Actions) else do (Else Actions)
Let's get started on it.
First make an if/then/else Action.
This helps it when a unit picks up an item, if the unit already has a weapon it wont pick up the new weapon.
Now for the If - Conditions you need to make:

(Item-class of (Item being manipulated)) Equal to Artifact

Only1Weapon1 Equal to False
What this does is it lets the trigger know if the item being picked up is a weapon and checks if there is already a weapon being wielded.
Now we got that down we need to make a Then - Action this is what it should be:

Set Only1Weapon1 = True
This simply tells it that the unit has picked up a weapon.
Now for the Else - Actions you need another if/then/else.
After you make another if/then/else in the else action you now make some If - Conditions.

(Item-class of (Item being manipulated)) Equal to Artifact

Only1Weapon1 Equal to True
This will tell it that there is a weapon in the inventory yet and doesn't not let the unit pick up the weapon, goody? nope, its not over yet
now for the Then - Actions you make the following action

Then - Actions
Well, this is just a helpful thing for the second trigger you made,
"Able2PickUpAfterDrop1"
and tells it what to do with a weapon if the unit is not able to pick it up, also a little user friendly text message that informs the owner of the unit trying to pick up 2 weapons that you can only wield one weapon at a time.
in the Else - Action create another if/then/else action.
For the If - Conditions in the newly created if/then/else, do this:

(Item-class of (Item being manipulated)) Equal to Artifact

Only1Weapon1 Equal to False
This lets it know that there is no weapon in the inventory and that the item being picked up is a weapon, easy?
Now for the Then - Actions:

Set Only1Weapon1 = True
Nice huh? This tells it that a weapon has been picked up and put into the inventory of unit owned by player 1 red.
And in the Else - Actions:

Do nothing
Short and sweet.
Now lets get to that second trigger.
"Able2PickUpAfterDrop1"
Create an Event:

Unit - A unit owned by Player 1 (Red) Loses an item
Now create an if/then/else action, and do the following:

If (All Conditions are True) then do (Then Actions) else do (Else Actions)
NOTE: My weapon classes are artifacts, you can also use permanent or charged or whichever class you want, but all weapon have to be in one class and armors in another class, don't use anything BUT weapons in class artifact if your weapon class is an artifact.
To use this trigger for all 5 players you need to use different variables and more triggers. EX: Player 2 blue's trigger - One1Weapon2, P2 Blues Variable - Only1Weapon2
Credits: World Editor (Of course :))
Written by TaaZ