Thought the original was missing something but couldnt quite think what? Well this is it!
Unfortunatly the game did have a few problems and the biggest complaint people would often level against it was that by late game defending your colonies from attack was pretty much impossible without diverting a large fleet to kick hostile fleets out of your territory. The reason for this was simply that, although you had access to orbital guns and the like to ward off attackers, the static defenses available to you became totally imputent within a few hours of play when the sheer size of enemy fleets just outpaced what you could field in orbit, even after upgrading!
Entrenchment is ironclads answer to this flaw. Billed as a "micro expansion" this small expansion for Sins concentrates entirely on (as the name implies) defence.
And what a difference it makes! Upon launching a campaign you are given access to a dedicated defense tech tree in which all your new defense options are organised to research. It adds everything you could possibly need to protect and fortify your previously harmless colonies from hostile attack fleets. You can research mines, which are proximity explosives that deal massive damage to any ships that wander into their range. You can research upgrades for defenses that were already in the original such as additional weapons for the terran guass cannon which serve to make them more potentent later in the game. But the highlight has to be the starbase.
The starbase is essentially a massive and very expensive orbital structure you can place in any gravity well. Armed to the teeth with every kind of weapon the game has to offer and heavily armoured they are a force to be reckoned with and, after upgrading, by late game they are practically indestructable if faced with anything short of a massive fleet. Though of course iroclad did see fit to give each race a counter unit to include in their fleets with which to combat these monsters so thankfully they do not break the balance of the game!
I keeping with sins tradition laid down by the original each of the 3 races is largely unique and as such their defense options are different from that of the other races in their own subtle, yet effective, way. For example the Vasari are the only race whos starbases are able to move around within the gravity well making them much less predictable than the those of the other two.
In short if you loved the original sins but ended up being frustrated everytime you had to cancel that long planned attack just to defend one colony then this expansion pack is definatly for you.