Many thanks for your feedback. I will add more versatile AI opponents, with different strategies and difficulties, in the next update. And hopefully also a tutorial.
The buggy rush is really hard to stop. I will put another AI as the first level. What helps to defend is:
- sync up production when you have more than one factory
- sacrifice some hitpoints on buildings. If balanced right, it is possible to tech-up, keep your buildings alive, and defend with one less factory than the opponent has