Let me explain: In the game you describe, your level of “Technology” is directly related to what level your starbases different production capabilities are. If in the scenario you described, where you build your starbase that specialized in weapons and defense near a potential enemy (although it doesn’t matter where it is located, not trying to bring strategy into this) is destroyed by an invading enemy, you’ve essentially already lost. Your other starbases aren’t cable of building effective combat ships, and the time/resources required to upgrade one of them to that point will likely mean the destruction or occupation of most or all of your empire.
You'd obviously need more than one production center. While resources come into play, time wouldn't be as much of a factor. You could technically go up 3 levels in 3 turns possibly, or maybe just in 1 (representing you brought people in to perform the upgrades to the infrastructure during that month).
In the base ref game I'm using it actually works well, and you can always end up promoting another starbase to do more than one thing, but you'd rather not if you can avoid it.
Also, try not to think of it as a "this starbase makes weapons" as much as "this starbase produces mid warships". All bases should technically invest some in engines, weapons, but in varying degrees depending on the resources you expect to be able to collect from the nearby planets, and the role the SB will play.
You would have some maxed out SBs to produce your top-of-the-line warships, for sure, so you'd survive the loss of a SB, but it would hurt.
The intent is also to shift the loss of a planet (in a galaxy so large, losing one planet isn't that bad, really) to the loss of an investment (starbase). When someone kills your starbase, they are sinking many resources:
- The initial resources spent to build up the starbase, and a fraction of the cost of all of the ships that had to ferry cargo there.
- The investments made in tech upgrades done to the starbase
While capturing planets denies potential (resources that has yet to be mined), losing a starbase outright destroys a portion of the game's finite resources, much like breaking ships would. Think of SBs like veryyyy expensive ships.
This is of course just my opinion, and perhaps this is even what you are aiming for (making starbases extremely important, and their loss almost game losing before you have multiple starbases that specializes in the same area). I find it slightly unforgiving though. I hate the feeling in a 4x game where a war between you and an opponent is decided in a single instant, or battle. Basically, I despise the “mop up” phase of a 4x, where you’ve basically already won/lost, and are just going through the motions of finishing the game.
Starbases would also have strong defenses, making it impossible (or so) to wreck in the early game. They could take on a few ships, unflinching.
Likewise, since SBs will be so strong, while losing would be crippling, building a new one would give you a sudden advantage. The intent here is that, if an enemy's advance has wrecked one of your SBs, you'll turn back, defend your next line of defense (possibly, your closest SB) and lick your wounds from there. They offer sufficient defensive advantage to insure your fleet will probably hold back the enemy there until more reinforcements come along, and you can probably build another SB in a different direction during that time, to reinforce your line with even more ships, or better techs.
I think your concern is valid, but can be kept in check with clever balancing.
Is losing a war in a single battle realistic? Absolutely. Is it fun? Not really. If I lose a key planet or asset, I still want there to be a way for me to claw my way back into the game, or at least go down struggling! Losing the ability to produce an effective military after a single loss would not really allow for that.
As previously said, the SB will be a strong static defense element. In other words, it will cost less resources per "firepower" unit than ships would.
Thus, it will always be more cost efficient to move back, build a base, and get your troops around it, than to build ships and strike. So, if the enemy intends to continue his pursuit, he either needs a very strong military advantage (which he has probably lost trying to defeat your SB in the first place), or he'll also need to settle down and build a new SB of his own to capitalize on the economic advantage he has gained, and slowly turn it into military might.
I think of SBs are production centers, much like expansions in Starcraft 2. You have to fight for them, and they grant you an advantage, but the amount of investment put towards securing the expansion means you'll also stop there, and not raze the whole map in one hit.
This is where techs come in: when you have built your SB, building up your techs insures that you'll need to spend some time including this new area of the map to your logistic plans, bringing the resources to raise its level, etc.
Your opponent (or you) should be rewarded for thinking about bringing freighters along with their fleet in an effort to kickstart a starbase and minimize the amount of time before their SB becomes a good production center.
I brought this up because I’m trying to find an effective way of eliminating this “mop up” phase from my own game. I want the player to still think they have a chance to effect the game even when they have almost been eliminated (maybe not win, but take some enemies down with him, and put up a fight of some kind). I want the player to still have meaningful choices that can have some kind of effect even if they’ve lost a key system/asset.
My personal approach to this is actually located in ships. Most 4X games assume that there is a drastic difference in power scale between ship classes (a destroyer has 10 times the firepower of a corvette for example). I reduced this so that 2 corvettes could easily take down one destroyer for example, and increased the cost of the destroyer nonetheless, because, at any given place, it would be stronger than any ship below its class. Concentration of power, in space, is hard to achieve: you want to cover wide areas, because players can always use that against you if you focus on strong ships. Likewise though, you'll need actual might to defeat Starbases, so you will still have to build destroyers, else, you'll lose too many corvettes in the process.
Phew! Sorry, at some point there I stopped commenting on your game and started discussing problems in mine! Anyway, this whole thing is just me throwing ideas and personal preferences around, so while I might find it unforgiving, maybe it’s just right for everyone else J
I'm ok with that, its good to discuss with somebody tackling the same problem. Unfortunately, I know too little about your project to really lend a hand, but I'd sure like to!