The hotbar is the vertical column of boxes on the right of your screen. It holds up to ten items that you want to use or place.
How to Use
Drag any item from your inventory into your hotbar, and then click or tap on that item in the hotbar to select it. If you play using a keyboard, you can select an item by simply typing the number of the slot. If you're playing on a device large enough to display all ten slots, you can select the tenth slot by typing a zero.
Deepworld allows you to set up to 10 different hotbar presets so you can easily switch between different sets of items/blocks. For example, if you're heading into a PvP battle, you might want your hotbar to contain bombs and your weapons of choice. If you're going exploring, you might want it to have your pick, shovel, a weapon or two, portable teleporters, protectors, and such. If you're working on an ongoing building project, you might want to have a certain set of construction materials or frequently-used items and devices at hand. If you assign each of these configurations to a different preset, you can quickly change your hotbar whenever you want with just a couple keystrokes.
Note that hotbar presets only affect items in the hotbar, and don't have any effect on how you've arranged your accessory bar.
Mac: To set a hotbar preset on a Mac, first arrange your hotbar to your liking. Then press the Command and Control keys at the same time as the number you want to assign to that preset. The game will notify you once you've successfully set a preset.
You can choose any number from 0 to 9. If you choose 0 (zero), the game will tell you that you've stored hotbar preset #10, but you can still call it up by pressing Command-0.
To call up a preset, simply press the Command key and the number of the preset. Your hotbar will instantly rearrange itself to your chosen settings.
iOS: On iOS devices, once you arrange your hotbar the way you want, you need to use the powerups panel to save and recall presets.
PC: As of this writing (January 2016), hotbar presets are not yet functional in the v3 build. However, if you set a preset using v2, you might be able to call it up by pressing the Control key and the number of the preset when you return to v3.
If you leave a slot empty whenever you go exploring, when you receive a brand new item that you don't already have in inventory, it will appear in your hotbar.
If you receive an accessory, it will always try to equip itself in your accessory bar. If your accessory bar is full, but you have an open slot in your hotbar, it will appear there.
You can monitor the moment-by-moment tally of any given item by putting it in the hotbar, which will display any increase or decrease in amount as you go about playing the game. Note that this figure is exact up to 1000, after which it counts by thousands. The game cannot accurately display item counts higher than a million, so if you have more than that of an item, it will show as 999k.
When visiting unpurified desert worlds, if you don't have immunity to dehydration, place jars of water in your hotbar so you can tell when you're getting low.
When trading or giving items, you don't need to first move them to your hotbar; you can drag them straight from inventory.