Half Life Gates ( Half Life 2 X Gates)

Warning contains cursing and sometimes things that's not for kids.

Over Years Earth was invaded by aliens called the combine. They took the planet easily and rule the planet. It was then hope was lost until Gordon freeman came. The humans then attack the combine while city 17 was then destroyed. Over months the war still continues but it was then another army from another world came that could be a disaster. Will the humans in their world saved the other world or the combine will just take it like earth did.