The Command Menu shown at the bottom of the screen during PvE missions or PvP matches allows players to control their building construction, unit production, in-game unit upgrades, defensive towers, and where their troops will arrive on the map after being produced. Hitting Escape while in any sub-menu will return you to the main Command Menu.
Building Production Sub-Menu
Clicking the Building icon or pressing Z from the main Command Menu will open the building sub-menu, which will display what unit production buildings can be created. If you have enough resources, clicking the building's icon or pressing the corresponding hotkey will start production back at your base. To unlock access to more powerful units, you must progressively build more advanced buildings.
Unit Production Sub-Menu
Clicking the Unit icon (creature symbol) or pressing X from the main Command Menu will open the Unit Production sub-menu, which will display what units can be created based on what buildings you have constructed. If you have enough resources, clicking on the unit's icon or pressing the corresponding hotkey will instantly produce the unit back at your base. After a unit is produced, a cooldown timer will count down until another of those units may be produced. The time it takes is based on how many of those buildings you have built, and your character's personal stat bonuses.
Unit Upgrade Sub-Menu
Clicking the Upgrade icon (the graph symbol) or pressing C from the main Command Menu will open the Unit Upgrade sub-menu, which will display what Attack and Defense Upgrades you have available to choose from for your units during that match. Upgrades for the first and second tier units may be unlocked after building the second tier building. Upgrades for the 3rd and 4th tier units may be unlocked after building the 4th tier building, etc. Three (3) Upgrades may be purchased for each set of upgrades, so choose wisely between Attack and Defense based on your play style.
Defensive Building Sub-Menu
Clicking the Tower Construction icon (the building with the shield symbol) or pressing V from the main Command Menu will open the Defensive Building sub-menu, which will display which defensive structures you can construct. Defensive buildings may be built only after the first and second unit construction buildings have been created. Defensive buildings may be placed anywhere around the map so long as your character is nearby, and include Walls, Repair Buildings that heal allied structures, and Defense Towers that fire on nearby enemy units and characters.
Clicking the Demolition Command (cross-hair symbol) or pressing B while at the main Command Menu will change your mouse cursor into a cross-hair icon that will destroy any unit or cancel any building you control. Useful for when you have more units of a weaker type you would like to clear population cap for, or you would like to cancel a building under production you have changed your mind about, or you need to clear a gap for yourself to move through in a wall you built.
Clicking the Rally Point icon (check-mark) symbol or pressing R while change your mouse cursor into an arrow symbol. Clicking anywhere on the map with the Rally Point indicator will make all units you produce immediately move to that location after they are produced. You may change the current Rally Point at any time.