You need experience points (XP) to level up. You gain XP by performing actions in the game.
Levelling up unlocks skill points (3 SP per Level-up) that can be used to customize your gameplay attributes. It also expands your inventory capacity, energy capacity and increases your chance to receive higher level weapons/mods as loot.
You also gain 5 Time Marks (TM) per Level-up.
Inventory capacity can also be increased by buying extra inventory space with TM (click red (+) button in upper left corner of your inventory). Energy capacity can also be increased by energy modules.
XP table for game version 9.78
|Level||XP needed for this level||Energy capacity||Inventory capacity|
Levelling up screen
XP gained for actions
|Plant a core seed||250|
|Plant Base Seed||???|
|Capture a white core||???|
|Upgrade a Mine one level||250|
|Upgrade a Core one level||100|
|Upgrade a Base one level||500|
|Add Mod to Core||10|
|Add Mod to Base||10|