Humanity finds its place amongst the stars and together with others they stand united under one purpose, to survive never-ending onslaught against a merciless enemy. Now on the brink of victory and with a new tool to use and new territories to claim, will this victory lead to an age of peace and prosperity or another war. (Warning: Changes in mass effect lore, rated M for safety)

On September 20th of 1963, John F Kennedy proposed a joint Soviet-US Moon mission. In our timeline, Kennedy was assassinated before Premier Khrushchev could respond. In this timeline, Lee Harvey Oswald fails and Khrushchev accepts Kennedy's proposal. See how one different decision changes the following events. (I'm not good at summaries)

The 1st Exploration fleet under Admiral James Anderson enters Gargantua to explore a new world and stumbles upon the Mass effect Universe. How will the Citadel species react to another humanity that freely uses AI and Dragon lookalikes with access to the Shroud? Only time will tell.

10,000 years have passed since the Scourge destroyed Earth. The Migrant Fleet awakens its first 400 Passengers out of 10,000, the best young adults and teenagers we had to offer above their destination planet, a frozen world. These 400 will first need to build a human base on the planet and help reform their species' future either diplomatically, or by an Iron fist.

Four hundred years have passed and the galaxy is prospering. Commander John Shepard has become the galaxy's most favoured hero and most if not all sentient beings strive follow in his examples. For Amanda W. Shepard, she has to live up to her ancestor's legacy and lead by example, top of her academic and military classes, she is stressed out. Things are about to get more stressful.

It will not by just a stellaris crossover, there will be universes like warhammer, Beyond Earth and Starcraft

A fusion fic between several sci-fi settings, including Mass Effect, Star Trek, Star Wars, and Warhammer 40K. Humanity long ago built a might galactic civilization. But then, the Age of Strife happened. Now, the remnants of mankind-as well as many alien species-struggle to rebuild and great men clash to shape the future in their image.