Designing an Inventory System

I want the player to be limited in what they can carry, so the inventory will have a set number of slots (like Minecraft or Stardew Valley). Perhaps later in the game they will be able to add additional slots, since it makes sense that they will become stronger over time. They might also be able to acquire additional bags, which would add more slots to their inventory. 

UI Design

The initial inventory should be simple and minimalistic (but not ugly). 

When the player rolls over an item icon with their mouse, a tooltip should appear with the name and/or description of an item. Its price (if applicable) can appear at the bottom of the inventory UI. 

I'll also need items for the player to pick up. In the current environment, things like plants and flowers (alchemy ingredients!!) can be expected, and a lootable chest would also be easy to implement. That means I'll need a UI for looting fallen NPCs and other containers, which should look like a smaller version of the inventory UI, probably with a list of item names instead of icons. 

I have uploaded an image of the prototype I made, which actually turned out pretty cool! It has the warm colors, simple, minimalistic design, rounded edges, and some simple icons for demonstration's sake. 

I will need a pixel art font for the quantity display, as well as one for the quantity of gold the player is carrying (to be displayed bottom right).

Programming Considerations 

With this inventory setup, the player can have a maximum of 40 items. These items will probably be added to the inventory (array of fixed size) as they are picked up, but a drag and drop system for rearranging items may also be possible. I plan to follow a tutorial for the most part, but the functionalities needed include picking up, dropping, and using items.