So, whats the incentive to fight exactly.

Near as I can tell, you leave 1 ship in each system you colonize completely, and then never give that ship any orders. This pretty much guarantees your income stream is undisturbed. It also would really frustrate any other player in that system.

I know its early to venture an opinion, but the old 'pay for winning a system' encouraged conflict, whereas this does not. Anyone have any ideas on how to address this?

if there is a ship in-system slow the rate of income to the first time a turn is run in system after a galactic turn has run. in other words; the slower of the two turn rates. suddenly you have to do +something+ to get the cash, even if just moving around, thus you can't leave a safe cash flow that accrues even if you aren't playing. This will frustrate invaders less becuase they can suddenly invade at a speed slightly faster than a glacier, or be comforted knowing that their opponent is loosing credits to the pace.

if no (friendly) ships exist in system credit accumulation can be left unchanged.

Hmmm, similar idea to Mortis. If an enemy ship is in system, then that system is blockaded. The owner of that system earns no money from the colonies within it, that income instead goes into a pool related to that system.

The winner of the system gets that money in a lump sum (so if its your system then you break even by winning). If the attacker wins, its viewed as 'pillage' etc.

I really like that idea, I'd still slow the rate of accumulation simply as a limiter on how much cash can be generated "for free," but the blocade idea is great and should do a lot to encourage individuals to jump into high productivity systems and steal their income. What about a system with no friendly ships but enemy ships? The enemy ships ought to hijack the taxes.

I was thinking something a little similar.

eg up to 15 credit from the colony accrues on its own - resupply shuttles or whatever carry it in small cargo holds.

BUT, to get the rest you must sponsor a cargo run from your homeworld. And then protect those ships....or something.

ie they are automated.

effectively, whatever ship runs the turn (if no conflict exists) gets the cash? If no ship is presant the cash sits until someone runs a turn?
I wouldn't have them deliver the first 15 on their own. Just as a function of (in "character") logistics- that's the least likely portion of a tax base to be able to self-provide.

1st 15 is from size 3 colonies - it's not tax, more their job. i.e. the profit from you funding/founding the colony.