These are a couple ideas I came up with while playing GalCiv2. GalCiv2 is absolutely AWESOME and the most loyal-to-the-original game sequel I have EVER seen! I love the gameplay, and I'm convinced it is the most comprehensive sci-fi civ game there is. That being said, no game is perfect and nothing has everything. These ideas are my thoughts on (hopefully) how to keep GalCiv in the expansion-pack business and improve gameplay/replayability. Normally I'm too busy to frequent forums, so I saved up my thoughts to drop them in one mega-post, so my apologies to the length.
DISCLAIMER: I am not an experienced modder, I have never programmed a computer game, I have never had a game published or produced. This should be kept in mind when seeing my ideas, as they are merely organized and detailed suggestions. I figured it was better to put some thought into it and give a fully-formed concept rather than a vague idea. Assuming the developers consider my ideas not sucky (or maybe at very best think they're worth looking into) at least they'll have some sort of skeleton to tinker with.
New Anomaly
-Entropy Effect: Frequency 1/50. Randomly causes 50 new anomalies to spawn across the entire map. This will keep the survey module useful into late game, and one of my favorite parts of this game is exploring anomalies, so I've been dying for a respawn mechanic since GC1!
Dropship Tech Tree:
It always bothered me that my transports weren't reuseable. If I were going to invade an alien civilization, I certainly wouldn't throw away my troop transport after one use! But, of course this is a much-needed gameplay mechanic to make troop transports affordable without over-powering them. So... I came up with the idea of advanced transports that use dropships. Dropships fit into the GalCiv2 tech tree by branching off of the currently existing tech, Advanced Troop Mod. This allows players to heavily armor or arm their troopships without fear of wasting resources.
A suggested Dropship Tech Tree:
[Advanced Troop Mod]--->[Dropships I/II/III ]
Dropships I
-New Ship Component: Dropship Pod
+1 Beam weapon defense, holds 250 legions (250,000 troops)
A ship equipped with a dropship pod gains the option to detach that pod. When a pod
is detatched, it becomes a ship with 1 beam weapon defense, 1 hit point, and a
movement speed of 1 parsec per week with range equal to the ship that carried it. The
now detached craft has 250,000 troops plus the ability to invade a world, and the ship
that detached it is now carrying 250,000 fewer troops. The 1 beam weapon defense is
the dropship pod's heat shield that allows it to survive planet fall. When the ship
that was carrying the dropship pod goes someplace to pick up more troops, it must
spend the cost of a dropship pod to take on new troops. Ships with multiple dropship
pods would have to spend that cost multiple times (once per pod/250,000 troops).
Dropships II
-New Ship Component: Enhanced Dropship Pods
+1 beam weapon defense, holds 500,000 troops
Dropships III
-New Ship Component: Ultimate Dropships
+2 beam weapon defense, holds 500,000 troops, and detached pods move at 2parsecs/week
Special Forces Tech:
I like stealing things from my opponents, especially when it's an incredibly valuable starbase sitting in my space that they won't trade to me for anything approaching what I consider a fair price. So... that's when I'd like to send my Empire's Special Forces to board that station and take it by force.
[Stellar Marines]-->[Special Forces I/II/III/IV ]
Special Forces I: Basic Engagements
-New Ship Component: Special Forces Barracks I
When a special forces ship attacks a cargo hull ship, it boards that ship. When a
special forces ship is attacked, combat proceeds as normal. Holds X SF troops
Allows automatic capture of cargo hull ships (Special Forces ship is spent on use).
Special Forces II: Military Targets
-New Ship Component: Special Forces Barracks II
This allows a ship to board a medium-hulled ship.
Special Forces III: Capital Ships
-New Ship Component: Special Forces Barracks III
This allows a ship to board a large-hulled ship.
Special Forces IV: Command Ships & Facilities
-New Ship Component: Special Forces Barracks IV
This allows a ship to board a huge-hulled ship or a starbase.
Calculating ship to ship invasions:
Advantage Points calculated as normal, with the following bonuses:
Attackers:
+1 per SF Module (these are highly trained special forces, not standard troops)
Defenders:
+2 for large ships, +3 for huge ships
+1 per 2 levels of the ship
+3 for economic/cultural starbases with an additional +1 per every 2nd module.
+4 for military starbases with an additional +1 per every 2nd module
Carriers Tech Tree:
Carriers are a major component of several sci-fis (Battlestar Galactica, Farscape, Wing Commander, Star Wars) as well as modern day warfare.
While fighters are constructible in GalCiv2, short range attack fighters or slow moving "bombers" are not useable in the offensive side of GC2 warfare. The suggested carrier tech tree would branch off of the currently existing Space Militarization Tech.
A suggested Carrier Tech Tree:
[Space Militarization]
..|
.\|/
[Naval Carrier Adaptation]
..|
.\|/
[Fighter Support I/II/III ]---->[Fleet Support I/II ]
...........................\
............................\-->[Galactic Scavenger I/II/III ]
Naval Carrier Adaptation
-In-Game Tech Explanation:
While carriers have long been a vital component of naval strategy for centuries now,
it has taken our scientists quite some time to develop the necessary technologies to
support the development of space-based carriers. We are now ready to get to work
designing our race's first ever star fighter carriers!
Fighter Support I
-New Ship Component: Fighter Bay
Allows small or tiny ships in fleet with this ship to use its speed and range in place
of their own, normal logistics restrictions for fleet creation still apply. (This is
gonna have to be a HUGE and expensive component to compensate for the awesomeness of
this ability. If it went on a medium ship there barely be room for anything else.)
Ships with Fighter Bays have the option to spend the rest of its move to "deploy."
When deployed, a carrier (meaning any ship with a Fighter Bay) becomes stationary, but
gives a radius of support allowing for fighters to separate from the carrier to attack
targets. An in-game explanation for requiring deployment would be that the fighters
require a stationary reference point for proper operation. When a carrier "undeploys"
it has zero move actions. This would give players the ability to deploy short range
fighters at great distances (thus saving room on ship designs for more weapons or
armor). Allowing the "deployment" feature would even let players produce inexpensive
carriers through the use of cargo hulls while avoiding the risk of losing their
carrier in combat with the trade-off of being strategically vulnerable. Plus it would
just be f-ing awesome for all us fighter fans.
Fighter Support II
-New Ship Component: Repair Bay
Grants a repair bonus to tiny or small ships in fleet with it
Fighter Support III
-New Ship Component: Extended Fighter Bays
Allows X free logistics points that MUST be used on tiny or small ships.
Fighter Support III, Alternate concept
-New Ship Component: Construction Bay (possible new starbase module?)
Allows construction of tiny or small hulled vessels, but is restricted by the number
of pilots the ship possesses.
Fleet Support I
-New Ship Component: Repair Facilities
As repair bay, but grants the repair bonus to Medium, Large, and Huge ships instead of
small or tiny ones. The ship now has a docking bay filled with shuttles and staffed by
engineers that can perform repairs on nearby vessels.
-New Starbase Module: Dry Dock
Allows construction of a Dry Dock at starbases. A dry dock will fully repair a tiny,
small, or medium ship in one week and a large or huge ship in two weeks. The down
side is while under repair at a dry dock a ship has only 1 hit point (just like when
they are being upgraded). A dry dock may only have one vessel in it at a time.
Fleet Support II
-New Starbase Module: Dry Dock II, Assembly Line
Dry Docks now have the capacity to build starships! Thanks to the benefits of zero
gravity, ship construction at a Dry Dock progresses 10% faster than on similar
planetary facilities. Dry Dock equipped starbases within 2 parsecs of a
player-controlled world will use that planet's stats to determine production speed.
Otherwise, they will use the starbase's crew complement (listed in the intelligence
report) and the production value of an initial colony plus any production bonuses from
itself of other nearby starbases.
Assembly Lines grant a starbase 10 manufacturing points.
Fleet Support III
-New Ship Component: Docking Bay
As fighter bay, but applies to medium ships only.
Galactic Scavenger I
-New Ship Component: Salvage Bay
Recieve 1% of the cash value of enemy and friendly ships destroyed during combats this
ship is involved in.
Galactic Scavenger II
-New Ship Component: Improved Salvage Bay
Recieve 2% of the cash value of enemy and friendly ships destroyed during combats this
ship is involved in.
Galactic Scavenger III
-New Ship Component: Superior Salvage Bay
Recieve 5% of the cash value of enemy and friendly ships destroyed during combats this
ship is involved in.
These thoughts are free for anyone to use, providing that the results are shared on this site in one way or another (crosses fingers for carriers in the next expansion pack). I hope this post is useful to someone, but if it's not at least I put all my ideas down into a single useless post rather than 5 useless posts.

I am aware of the deadness of the "carrier" issue, but have not moved that segment of this post to the carrier post because of the salvage and fleet support techs I based off of my suggested carriers tech. I did however move that portion of my suggestion to the absolute bottom of the post to downgrade it's importance.