Last time I taught you to make a simple plant colecting system. Now I will show you what to do with these plants. This will be simple alchemy system with minimal scripting.

The system will be very simple, but expandable. It will combine two items and give you a potion depending on the items you used. First item will determine the effect, second will determine its strength. Plant and a flask.

Make a room and four events. One of them is optional, but I will use it for geting new ingredients
(the chest). This is a example:

It is time to prepare our ingredients. Potions will require two components. Plant, that determines the potions effect and a flask, that determines its strength. We will also need one useless item for testing and the potions them self. I will use only two ingredients and three flasks so this is how my database will look.


The "rock" is not really important. You can use it for testing puroses or not add it at all. It is up to you.

Go to the "system" tab in the database and add an "ingredient" element. You will need that later. Also, don't forget to asign EMPTY common event to every ingredient. Plants and flasks. I named my ALCHEMY.

Now we will need to do some scripting. This will help us to determine what item ID we used. Open the script editor and find "Scene_Item" and find the spot you can see in the picture, Insert the highlighted code here.


Here is the code if you want to copy it directly:

# Change variable to used item ID if it has the "Ingredient" element
if @item.element_set.include?(1)
$game_variables[2] = @item.id
end

Change the "@item.element_set.include?(1)" to whatever the ID of your "ingredient" element is "$game_variables[2]" will be the ID of the ingredient item you used. You can use a different variable.

This little script checks the item with common event asigned. If the item has the "ingredient" element, it will store its ID in the variable "2" so we can use it later.

Now it's time to start working on the ingredient spots. Open the first, leftmost event.
This event will be used for storing the "effect ingredients", in my case, the plants.

First, we need to tell the event what items are actualy the plants. Check you database and find the IDs of your effect items. In my case, healing plant (1) and stamina plant (2).

Create a array called "@effect_array" and put your IDs into it. This is how it's going to look for me:


Now we should reset the variable with the stored item ID. The same variable we used in the script editor. In my case, variable 2. This is done for one simple reason. Player might have used the item somewhere else by accident. This would still store the item ID in the variable and it might screw few things up so it is good to reset this variable before we actualy use it.


Then we need to open the inventory screen. Use this script code.


Here is the code itself:

$scene = Scene_Item.new

Player will sellect the item he wishes to put into the slot. The inventory will then automaticaly close. This is thanks to us adding empty common event to every ingredient.

Now we need to add a conditional branch.

This branch will check the "@effect_array" and see if any of the numbers inside are shared with the variable 2. If it is, the variable 2 will get stored in another variable (3) and player will loose the item. If it's not, player will get a message telling him he used wrong type of item.


Don't forget to reset the variable "2" as the last thing you do in this event. Also set up the page 2 of this event like in the following picture.


Now open the event rigth next to it. This event will be basicaly the same. The only difference is the array at the start and the variable for storing correct item ID.

Create new "@catalyst_array" and put your second batch of ingredients into them. In my case, small, medium and large flasks (4,5,6). Change the conditional branch acordingly and don't forget to asign the item ID to different variable (4 in my case). Change the second event page too.

Now open the last event. This event will give us the resulting potion. This is how the entire thing looks.

First two conditional branches check if there is any item inserted in both slots. If not, the game shows the player the message saying he needs to put items in both slots. If both slots have items in them, the game starts checking the combinations. This is the condition:

"$game_variables[3] == 1 and $game_variables[4] == 4"

"$game_variables[SLOT_A] == SLOT_A_ITEM.ID and $game_variables[SLOT_B] == SLOT_B_ITEM.ID"

You wil have to do all combinations manualy so it is good to keep the amount of possible combinations manageable.
Don't forget to set both item slot variables to "0" after you get your potions.

And that's it. The system is pretty simple and straight forward. It can be easily repurposed to something completely different, like combining mold and metal to make weapons or magical stones and paper to make scrolls.

There are plenty of scripts focused on crafting, but this is a good alternative if you want to make something more interesting than a simple menus.

Hope this guide helped you. You can always ask me here if you end up having problems or questions.

And here is the result: