Super Robot Taigen OG Saga - Endless Frontier (2017)

From the introduction:

What made this world the way it is…? Some have said that it has existed like this for tens of thousands of years. Others have said that it was always like this.But, not a single soul knows the truth...Only one thing is known for sure. The worlds are infinitely far apart, yet are extremely close , connected by a series of holes in space known as Crossgates. At first, contact with people from other worlds created great confusion, which in turn led to conflict. A chief conflict in this world was known as the Ten Year War, between the dark dimension Formido Heim and the fantasy landscape of Elfetale. However, this war ended as all wars do and peace was maintained with a delicate balance of power. But 18 years ago, the wreckage of a battleship from another world crashed down. This even will, in 5 years, lead to the events that will change the history of the Endless Frontier forever.