This game needs mod capability if it is to last a long time. Look at the two most well knows games with moding capability like The Elder Scrolls Skyrim, and Minecraft. If ether of these two games wore standalone they would have not lasted as long as they have.
I understand that the games are completely different to GDT, however, being able to have the ability to add new features created by individuals playing this game would open up many more sales and longer playability for others.
It might be to late to do this, I don’t know, I never created a game. However, I know that if you allow people to create more content for your game then that is sure to make everyone happy.
Just me thinking out loud.