Local Co-op is when multiple people play a game using the same computer.
To play Nom Nom Galaxy with Local Co-op:

• click on Corporate Conquests
  
• look near the bottom of the screen, and make sure it is in offline mode
  
• start up a game by clicking on a planet
  
• Once you can move, press the start button on controller two OR the enter key on the keyboard

Only Controller Two Can Join The Game
Only Two People Can Play Local Co-op
(If you press Start on controller three, nothing happens)

To play with 2 or 3 friends, you need to play online. To play online, everyone needs a copy of the game on different computers. Then,

• Click on Corporate Conquests
  
• Click on Go Online
  
• Click on Create an Online Game
  
• You will see this, and you can click on Invite Friend to invite a friend.

A Game Can Not Be Local Co-op And Online At The Same Time
(If you press Start on controller two during an Online game, nothing happens.)

There are two ways to join other player's games. The First way, you join a random game. Simply press Quick Join in the main menu. The Second way, you can narrow down the types of games you join.

• Click on Corporate Conquest
  
• Click on Go Online
  
• Click on Online-Search Options
  
• You will see this
  
• You can click the arrows to change the settings
  
• When you click on Search for Online Games you will see something like this