Another campaign idea I had but never did.
Fall of the North Star
Set immediately after the Epsilon Pegasi campaign, at the time while the player was doing his undercover loop and flying in the nebula with the Barracudas, but before the NTF's final charge.
The player is part of the NTF vanguard fleet based in Polaris, assigned to the NTD Vasa, which is based in Polaris, the capital of the NTF. With the Epsilon Pegasi system secured by the GTVA, Polaris is now open to allied attacks. The NTD Vasa has been assigned (along with the player) to defend the capital of the NTF.
The first mission would be a blockade mission of the Epsilon Pegasi node, while GTVA expeditionary forces enter the system which the player must bomb. Defending the node on the NTF side are the NTD Andronicus, NTC Camisard, NTC Gaouzu and NTC Fronde. After a very long battle, the Colossus enters the system and destroys the NTC Camisard, and then the NTD Andronicus. The player retreats deeper into the system.
The second mission would be a defense-and-evac mission of a military installation housing research stuff for the Knossos portal and related to ETAK. After a pretty long and gruelling battle, the Colossus enters the area and blows the installation up, but (depending on whether the player protected enough Evac Transports), the research data is recovered.
The third mission would be trying to attack the GTVA Colossus, which has been spitting out lots of fighters to attack system-wide targets in Polaris and generally giving the NTF a hard time. The attack group is very large (all active NTF destroyers deployed available assets) and attacks from all directions, not really in an attempt to destroy the Colossus but rather just to occupy it and stop it from doing any further damage. The player must attack the Colossus' escort, which consists of several cruisers and corvettes. When enough damage has been inflicted, the escorts withdraw and leave the Colossus on its own (the GTVA believe it can defend itself). The player attacks the Colossus, and to his dismay his weapons do no significant damage whatsoever. Eventually, the GVD Psamtik, GVD Memphis, GVD Toeris and GVD Hedetet jump in (ho boy thats a lot). The GTVA announces that Sirius has fallen and that the Vasudan 11th and 13th battlegroups have breached the NTF's perimeter.
All remaining NTF forces are to withdraw to Regulus, but the Regulus-Polaris node is surrounded by a dense asteroid field. The NTD Vasa, NTD Uhuru and some other NTF warships are retreating through the asteroid field, the player must kill rocks and the relentless waves of Vasudan bombers attacking the retreating group. After the large portion of the group has jumped out, the player must sacrifice his life in a hopeless battle against the GTVA (since he does not have intersystem warp drives).