>>6-8
The thing with these games is, quite frequently all I have to go on is a name and a release date. The first one I found was 505's "Monster Attack: Invasion" on one of the .nl sites, which I assumed to be Chikyuu Boueigun 2. But Essential Games' listings started appearing on amazon.co.uk, and since Invasion had only appeared on the Dutch sites I though 505's release had been cancelled and it had gone to Essential instead, as Global Defence Force.
Then a cover for GDF was posted on Amazon featuring art from the Japanese Tactics cover, and some of the .nl sites updated the release date for Invasion to later in July - they must have got that date from somewhere, indicating that Invasion was still on. So it seemed to make sense that Invasion is Chikyuu Boueigun 2, and GDF is Tactics.
Still, though, I really have no idea if any of that is true, and I won't really know until one of the companies releases a description or some screenshots - it's possible that, since Essential is actually D3 Europe, they have access to all of D3's art library and just chose to use the Tactics art for CB2. And it's equally possible that Monster Attack Invasion actually isn't anything to do with the Chikyuu Boueigun, and it's just another of 505's generic names (like "Space War Attack"). It's even possible that Invasion was Chikyuu Boueigun 2, it was cancelled and the Dutch distributor just didn't know about it.
So, yeah, basically I have no fucking clue.