Neil_Ads
our MC can get points from missions that the systems give him, and the system can get upgrades. and with the upgrades it open a store, and with every new upgrade the store get new categories. like: first upgrade he can get a few items like weapons, when this category of the store weapons will be upgrade later, there can be more and more powerful weapons he can get with the points from the system, we start with a few normal weapons, and when the system upgrade more, it open a store for books skill he can use himself or sell, again a few at start and simple skill books, just after upgrades of this store category, he can get more and more powerful skill books, and the same can go to eggs, he can get from a new store category, and as this eggs store category will be upgrade later he can get from the upgrades more and more powerful eggs he can buy with his points. hope that my ideas can give you new ideas, ( you don't have to follow what i say, just good ideas for you to think about )