The inventory is a very important part of the game. That's what the player is carriying on it's backpack. It's where materials goes when you grab them. That's where the materials are taken when you build something.
Tanks to high technology of molecular compression, the player can carry a lot of materials without being limited by the weight.
You can open(and close) your inventory with the "i" key.
The inventory is split in 3 zones.
The central zone is the storage zone. That's where materials are taken when you build something.
The higher zone is the tool zone. A tool is a functionnal device mapped to the players control. The tool stored in the leftmost slot is active. The other tools are not active. The player can switch between tools in the bar using the "F" key. When you start the game, you start with a tool in your bar, the default constructor/destructor. Don't move it until you get another one.
The lower zone is the powers zone. Powers are technical devices adding capabilities. Unlike tools, all powers in the bar are active at the same time.
You can see in your inventory some stuff that you saved from the crash. Be carefull not loosing this stuff.