We would love to add online multiplayer to the game in the future. We decided that it was not in scope for version 1.0 for various reasons. Programming online multiplayer is expensive and it requires a lot of testing and maintenance. There are ongoing server expenses to consider as well.
Since Aeon's End is a cooperative game, there will be alternatives you can use to play multiplayer until we can add it to the game. You can have multiple players use the same computer (hotseat or pass & play), or use screen sharing via Discord, Skype, Google Hangouts, etc.