In addition to solid gameplay mechanics and making possible the development of mods that went on to become franchises of their own, the Half-Life series gave us a story that was identical in terms of historical development ... right until you started the campaign.
Set in the shoes of a "simple" scientist working at a research facility, you start the game doing the mudane things every other working person does: talking to coworkers, putting on your work clothes, going through security checkpoints, etc. ... And then all hell breaks loose when you and your geek squad accidentally open a portal to another dimension that is dominated by a multidimensional empire bent on conquering everything they can.
If this premise isn't interesting enough, the second installment is even more intriguing by informing you that the multidimensional empire, The Combine, managed to defeat the whole Earth in less than a day. You go from MIT-educated scientist running around a top-secret research facility in one game to fighting guerilla warfare and inflitrating Combine strongholds in the second.
The Half-Life universe portrayed an alternate version of Earth that was subjugated by an alien force and at the same time showed an unlikely alliance between humans and another persecuted alien species with their common goal of liberation from the conqueror's fists.