Hmmm...
I can suggest next thing:
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Edited
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What about "to break" a game in two-parts, first part - regular prospector game, second part - another adventure after retire (more detailed) -
[spoiler="spoiler"]Captain after few years of retirement returns to active prospector *duty* (in desperate need of money or cuz was too bore etc) in another newfound sector (where you can found generated special planets that where missing so far. Yup, also need to reduce a number of SP generated per sector) where he buys a new ship on saved money(or takes as gift from old comrade) or uses old (see below) one. During that adventure captain can found special warp jump engine which can be used to travel between sectors (bring in mind another class of sp - superunique planets - 1 per sector and exclude all another of some class... oh and special multisector puzzles
... at good side you can have a persistent galaxy (also uses another generated sectors - maybe save sector with specific sector name?), at bad side - total size of it (in mb, later gb)). That sector much more dangerous (turn *****; you can call it hardmode)
Retire assets:
That things can not only add some score points but be a really helpful:
Wanna to save your fancy ship? In order to do it you need a really high rank and nice planet to keep it in garage.
Wanna to save ALL your artifacts, cool equipment and your experienced crew? Only for Dukes with really expensive domains!
Just a planetless knave? Duh - you can keep only your personal equipment and all your moneys.[/spoiler]
P.S. Spoiler tag still broken?
Sry for my engrish - i'm just a hamster
Space hamsters are never wrong!
Oh no! Its Wooly Rupert, the Tyrannohamstersaurus of Ill Omen!