So I've been playing this game since launch day and already clocked quite a number of hours, but one thing that I've noticed as I've played through with different map settings is that the maximum number of star systems that you can control before encountering the overexpansion penalty doesn't  scale up with the number of stars in the galaxy - as far as I can see in game, an Endless galaxy size has the same cap as a huge one, and the same applies to galaxy density as well. This means that despite there being additional worlds for colonization, the player and the AI cannot make proper use of them due to the morale penalty...so much so that trying to expand to cover even a single constellation of a huge ring galaxy with a high star density will destroy whoever tries it, since there are simply not enough happiness buildings to counter the effect. 


But there are a number of possible ways that this can be countered without seriously affecting game balance, any of which could be implemented on their own to solve the issue, with or without the other options. 


1. Tie the cap to the number of stars in the galaxy through the settings: I'm not entirely sure as to the logic behind the current cap, but a bit of simple math like, say, providing a fixed number of systems to each map that is then modified by the star density either upwards or downwards. A rough example would be - and this is based on random numbers from off the top of my head here - would be for a huge galaxy to be divided by ten to give each player a base cap of twelve stars, before factoring in the density modifier that would add or subtract fifty percent based on whether the density is increased or decreased. So, our players on the huge galaxy would have a base cap of eighteen stars if they increased the density or six stars if they decreased it. 


2.  Add a system cap slider to the game options screen: This one basically explains itself - a slider in the game options that can be used to set the cap according to a number of options that go from one quarter the normal, to half the normal, to the current amount, to half over the normal, to double the normal and to disabling the feature entirely. This lets people manually decide how many planets the people in their game should be able to colonize before encountering a penalty, with the lower options having a more tactical gameplay style to them due to the lower number of systems thus meaning less resources to hurl at problems and making the resources that they have available more valuable, ie, ships will be too precious to be thrown around with blatent disregard,  whilst the increased options would free people up to expand more on larger maps and have the reverse effect of the above. 


3. Increase the effect of cap increasing government types and technologies: This is really an option that works best in support of another, but which could be added on its own to slow down the pace of the game and make the technology choice more meaningful - in short, this would increase the benefits of the various cap-increasing technologies and governments to make them more useful in larger maps, with different versions of the technology for each of the different map types. This means that although people start with the same number of maximum planets that they have now, they can grow into a larger cap as the game goes on and thus start to fill in even a truly immense galaxy type over time, little by little. 


4. Lower the happiness penalty: This one is probably the most icky and difficult to implement, but the general gist of the idea would be that larger and larger maps would provide a smaller and smaller penalty to those who go over the system cap, since they control a smaller percentage of the galaxy than they would if they were to go over the cap on a tiny map, for example. This lets people expand as much as they want without too many difficulties from their system happiness and allows large empires to form, but maintains the penalty of expanding too much in that they would eventually run into penalties in line with the current game as they expand further. 


There's a number of ways that this could be added, but the main point is the same: to allow the player to choose just how big the nations in their game can get and to ensure that players can still settle the same rough percentage of the galaxy even on the larger map sizes without being penalized for it.