The planet's rescuer

Dear friend! Welcome to outer space, it is beautiful as always, but there are alien parasites in it, eager to destroy all life in the universe.
Our planet is no exception. The technology of allied alien beings has provided us with a powerful "orbital space tank" for defense, which has a variety of enhancements that turn it into a machine for exterminating opponents.
Our goal is to fight back and survive! Protect earthlings from attacks of alien space ships. Go and fight my friend!