how would playing a game of soccer, baseball, or basketball be different if inertia didn’t exist?

Well, assuming that the world would break if we didnt have inertia, in baseball, when you tried to catch a ball you would probably go flying backwards until other things stopped you (friction etc). you also probably wouldnt be able to run without the earth going all out of its path around the earth. every step you would take would push the earth because there is no inertia to keep the earth at one point

This is the answer: body 1 + engine 2