Ahhhh, my first post for any game in a LONG while (let's see, my last was probably to the Matrix Online). That say's a lot as I just haven't gotten into a game since then (actually, I was switching between WoW and Matrix, kept playing WoW way past Matrix, but went back to Matrix forums to check in on old clan buddies).
Anyways, I tried searching for a relevant answer to the Engagement Range. It lists Hold, Gravity Well and Local. Hold and Gravity Well are self-explanatory. Local has me a bit confused. Let me get some backdrop for you:
These x4 games for me are all about playing on an incredibly HUGE map with either max players or 3 players (and thus two opponents). I chose to have two opponents. I'm playing Advent. I like LONG games that I save and come back to. So, I start out in my local star system (out of 4 total on the map - with tons of planets, probably over 100). This map is HUGE. I love it. I pretty much go through the motions of setting myself up, colonizing planets and taking on pirates. I get to the point where I can finally wipe out the pirate base in my system and really just have to contend with my two opponents occassionally attacking with medium forces. All the while I make a push to colonize everything in my system. This obviously takes a while as I fight occasionally with my 2 opponents (some defense of 2 or 3 planet systems outside the star in the system, 1 with an artifact they keep going for).
Now, it takes me a while to get my whole system. I then start ramping up defenses and stuff on each planet. Particularly those in close proximity to the star. Okay, I know I'll get flamed but here is a little easter egg for those that like HUGE games but find it takes forever to get up cash. I would say its not a cheat. It's more like using HGH.
Sorry, Clemmy. ROFLMAO. Anyway, what I did after pretty much colonizing everything in my system was to save the game and THEN leave the game running while I AFK (er, go to sleep). At this point I placed a fleet at the Star to attack whomever enters, and a fleet at the planet with an artifact they keep going for. I think this would work....it doesn't.
I come back after about 10 hours to find that my system has been just about 1/2 taken over by one of my opponents. HOWEVER, I have over 300K in credits and way over 150K of each resource. It seems as if placing 1 fleet at the Star didn't work too well (the enemy just jumped to another planet). And the AI got smart and made a rush for another planet near the Star and then expanded from there, avoiding my other fleet at the planet with an artifact. I had some forces at that planet, but not enough for defense. NOW, I didn't want to retake my planets, it would have taken a day or so. So, I just went back through the autosaves (over 40 of them while I was AFK) and got to the point where they had taken over that one planet. From there I spent some time ejecting them, building up my planets and organizing a few fleets.
HERE IS THE ENGAGEMENT PROBLEM. What the heck does "Local" mean? To me, it should mean that I can set a fleet to be a roving defender in the local STAR SYSTEM. Thus sensing threats and reacting to them by going there IF, for example, its a significant threat and not just one enemy ship (although, the AI uses that tactic - for example, early in my game the pirates attacked me with a small force and I fell for it, meanwhile, one enemy took another force and went for my capital world -- HOLY END RUN BATMAN, that's some crazy AI).
So, does Local mean that my fleet would respond to threats in the Star system, or literally just in that little corner of the gravity well, cuz it would seem Hold would do almost the same, which is a waste. Waypointing won't work because if I waypoint around lets say 5 planets, all they do is jump around those 5 until they get to the enemy at which point all could be lost.
If not, then might I suggest that a Fleet have the ability to respond to LEGITIMATE threats in a system with a "Defend System" ability? The reason I ask is because I've made a push into an enemy star system and taken over one planet, and boy is it tough to go back and look after the other system. I just wish my fleet could be placed at the Star and if a large enemy fleet comes in and then jumps to a planet that MY fleet would be smart enough to follow. It's not perfect, because two fleets could come in, but hey, it's smart at least, no? It would even be BETTER if my fleet of lets say 100, would notice an enemy fleet of lets say 25, and then JUST break off enough of the Fleet that is somewhat equally matched to the enemy fleet WHILE the rest of the Fleet stays behind. This "sub" fleet could go deal with the threat and then rejoin later. Listen, it's not perfect, but at least its a little more intelligent.
Anyways, my large game is going rough - don't think my "cheating" (er, not cheating, using HGH to make me more competitive) to get creds/resources is really impacting the game, because ALL the while I was AFK the enemy was ramping up too. I have one planet in one of their systems, and they have allied against me. They keep attacking that one planet I have, so I eventually realized I have to make a push further into their system. I make a push and they attack IN FORCE. I was able to defend for a while but one of the enemy came in REAL STRONG, to the point where I lost the planet but had a small defense force there hanging on with all my defense beams/hangers. My main fleet got caught hitting two enemy fleets of equal/larger size. I had to call in the fleet from my home Star system to help. I can only kill two planets, not colonize them as I've lost the colony ships, oh and my mothership can't colonize because the system is too hostile. ROFLMAO.
What a game what a game. I hate you IronClad, for you have taken over my soul. I expect to be done with this game sometime this spring. 
Now, I'd play online if I could get this going with some dedicated players, so I'll try to co-opt some local friends.
This game must defenitely be used as a template for some MMORTSx4 goodness. Could you imagine where everyone starts out with a planet to take over, then joins other planets or other star sytems and then just everyone battles online in a persistent universe? Man the logistics would be crazy. Don't say it can't be done, don't you dare say it because some day it will be here AND all you MMO fans will LOVE it and be it's slave. LOL.