Sorry fellow Invader fighters!! I'd forgotten about this thread.
I'm still playing the same game. Granted it's not everyday, but I'm about 15 years past where I was when I last posted in this thread.
I think my issue with where the Invaders were first showing up had to do with the time incriments I was using, 30 days. That appears to have been allowing segnificant movement away from the wormhole before they were detected. This is inspite of having scouts at 4 points around the wormhole at 25m km's. I've since been using 1 day increments and have not had a repeat of the them first being detected several hundred km's from the wormhole.
My build up of several hundred missile fighters has been all that has allowed me to stay in this game.
I absolutely agree that the Invaders are way too powerful for races that start with research points under 1 million. My current game started with 300,000 rp's and I am bearly holding my home system. The economy is wrecked. Almost everything is being poured into new fighters generations and missile stocks to feed the fighters. What isn't being spent in those areas is either research based on wreck salvage or upgrading the remaining starting ships with new tech. No new ship construction has occurred in the last 8-10 game years.
Things are finally looking up. Radiation from the bombardment during the second incursion has disapated and the dust levels are low enough again that the massive infrastructure build is no longer needed. The infrastructure is being distributed to new colonies in the Sol system. Factory production is starting up again to replace the lost factories, mines, and research facilities. I'm having to very carefully watch the treasury and make sure too not let it dip negative for very long. The emergency buildup after the first incursion had a hugely negative impact on production and took almost 5 years to dig out from under.