Tips for the Invader Missions in Solar 2
The invader levels in Solar 2 are somewhat similar to the Nomad Love missions you faced as a planet, this time around facing larger amounts of forces that come in waves. The strategies for these group of missions is the same for each, with the only difference between the levels being a progressively larger amount of ships to deal with.
Generally speaking, you can spawn as a max life solar system, which you should have saved from use in the other missions and solar system building walkthroughs, and just duke it out with the aliens that attack you using your lifeform spaceships and turrets.
One important tactic is to always move around when a new wave shows up, as they typically gang up on a single one of your planets. You want to dart around to break up the attackers and get them interested in your spaceships versus your planets to avoid losing the extra life spawned by it. You can also try to get them interested in any nearby hostile solar systems or Life Planets. Other than that, the tactics here are pretty simple and straightforward.