FreeOrion

Right now, it's possible to make special hulls or ship parts that regenerate fuel (in fact, Bigjoe5 already did one).
So, perhaps some parts for fuel generation when stationary (may be tied to the current system's star and planets types) and a part that would refuel any ships of the same allegiance present in the same system.
Then, ships that need no ammo will go very far, but will have to stop and wait to regenerate fuel.

Also, outposts allow to form supply lines. Again, already implemented in Bigjoe5's ruleset, though probably this can be refined further - e.g. by allowing Max population of 0.001 or so on "bad" planets.

I'm reluctant to make it too easy to extend supply lines indefinite distances... At some point they'll end up being an annoying nuisance requiring the player to build a bunch of supply depots around the galaxy, rather than actual limits to where and how ships can operate.

As to the "supply ships", it would be a viable idea if supply is made differently.
E.g. like in ASC.
Not that carrying things around was a bad idea, it's just too unwieldy to do manually and automation requires extra programming which doesn't look like a high-priority thing. Also, trucks zipping around may both clutter screen and eat extra machine resources to process. For very small fleets it would be good and fun, but the more ships are here to supply, the worse it will be.
So if you don't want to care about it all the time, just assume there are many little lame trucks and the supply range is defined as supply ships' range in first place.


Of course, if it's too easy, it removes the very point to have any support system in first place. But if it's too hard to do in unusual circumstances, why not have one more option. Maybe, keeping a pile of non-producing, but resupply-capable outposts just costs too much. Also, outposts are hapless sitting ducks, so once the enemy hit the line, it's broken, and rebuilding it means more time and expenses.

In the early game, it's OK for ship's fuel to dominate how far they can go, with supply range being secondary, since the strategic game in that point won't involve a lot of blockades. Later on though, it's more fun if supply lines dominate fuel range so that blockades become a valuable and effective tactic. I don't really see building a lot of outposts ever becoming bothersome. If supply range is great later in the game, you won't need that many outposts anyway. In an unpopulated empire you can get anywhere fairly easily, sure, but if there are enemies cutting off outposts which could supply your ships further away than they can actually get back on their own, then that means trying to go deep into enemy territory is potentially an extreme liability, which is a good way to add range limitations without force-feeding them to the player as hard limits. It's best if such liabilities are dependent on the actions of the opponent, because that enriches the competitive game.

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