ya know what i'd suggest and rather than doing what most companies have done for these kinda games...
Sort out the Entire Story, sort out howto split up the game and then make the whole game.
Then release a part every week or maybe fortnite to make it just like a TV series, people deliberatly having to wait
That way there is no "Oh my god the next chapter will be 6months as there is an annoying bug in my level software.
As all that'll be update will the the level packs rather than entire game packs in the size of around 30Mb wouldn't be unreasonable, a few seconds download for Broadbanders and 2-4hours for Dialup peeps
Quite simple to make an Resumeable Downloader with DarkBasic Pro by pulling down the bytes of the a file and using the new file position command, you could combine it with a built in downloader so they download a small 800kb downloader which allows them to download the game once they use thier order confirmation code
Also been playing TheSimsOnline alot (week off this week so i'm just lazing about,should really be getting onwith my projects here but i want a break
) ... and it has an autopatcher system, i think that would be a good feature to include - like a seperate DarkBasic program that will update the original (or rather just install a new one, unless you fancey making a compare and contrast program - which is dang hard
)
but that way the use whenever they play the game, can always be updated so if there is and bug that prevents the use of a later level feature or you want to speed up the game.
Techically this would mean everyone who plays would have a beta style software, because there'd be less chance to test if your on a time scale to keep releasing - but allows you to update thier copies quickly and easily.
I'm sure there are a few talented peeps here who'd like to design a Resumable Downloader, Installer and AutoPatcher.
Anata aru kowagaru no watashi! 
