Return to the Deep (Part 2 of 2)

On a strategic level, I like the idea of XCOM using a massive surface-going ship as its mobile base of operations.  Smaller attack submarines could be deployed from it to intercept and disable alien vessels, while clean-up ops could involve lowering XCOM aquanauts down to the target location in a bathysphere.  Of course, all this begs the question: why go through all this effort to defend the oceans?  Well...XCOM: Terror from the Deep was unusually cognizant in that the game predicted rising sea levels in its near-future setting.  Less usable land means a refugee crisis, and a refuge crisis means large quantities of supplies need to be brought in to prevent widespread death and chaos.  Like it or not, ocean shipping lanes are the only way to transport large quantities of goods from one landmass to another.  Aircraft can do some of the long distance distribution work, but they too might need to travel over the ocean to get where they need to go (thus placing them in danger from sea-to-air attacks).

From an economic standpoint it's not hard to think of trade and commerce as tax revenue, and tax revenue as funds for XCOM.  If any step in that process is disrupted then that means less (or no) money for government-funded organizations.  If you would prefer a more sci-fi themed motivator though, there could be these massive Climate Nominalization Platforms (CNPs) that are similar to floating oil rigs in appearance, but in terms of function are used to reduce the intensity of hurricanes, typhoons, and cyclones.  Without them, population centers would be devastated (a fact the aliens are keenly aware of).

So, what about overarching alien goals?  Aside from making humanity miserable, it's always more interesting to give them a secret agenda that the player must discover over the course of the game.  In XCOM 2 it was the AVATAR project.  In the the original the ultimate goal of the aliens was to simply enslave all of humanity, but in Terror from the Deep they went a slightly more interesting route by drawing inspiration from the writings of H.P. Lovecraft.  When playing, it's easy to spot some parts that were influenced by "Dagon", "Call of Cthulhu", "Shadow over Innsmouth", and to a lesser degree "Whisperer in the Darkness".  Essentially, the aliens in XCOM: Terror from the Deep represent a different faction than those in the original game.  They came to earth long before recorded history and established a number of bases and depots beneath the waves.  There was a war, and while some strongholds were destroyed other more well hidden ones were preserved.  The inhabitants of these deep sea dwellings used their technology to enter a multi-eon long stasis.  Now that they have woken up from hibernation the aliens seek to re-establish themselves by reactivating their long-idle infrastructure.  Ultimately, their goal is to revive a powerful psychic entity capable of subjugating all of humanity.  How much of this story would play well in a modern XCOM game is hard to say, but one plot point I particularly like is the aliens resurrecting extinct forms of native marine life.  Perhaps they even modify each species cybernetically or at a genetic level over the course of the game to better serve their purposes.  Because the game takes place underwater, it would be interesting to have some really big sea monsters.  Conversely, very small parasitic organisms could be an excellent way to introduce some body-horror elements.  I also think some kind of swarming piranha-like enemy would make for an interesting bio-weapon or "living ammunition" for alien use in combat.  A substantial obstacle for advancing the storyline would be XCOM having to develop and build the necessary equipment to reach the deepest parts of the ocean in order to take the fight to the aliens.

The climatic finale of Terror from the Deep takes place on a fortress (called "T'leth") floating over the sea.  It's something that was reused in the Firaxis Enemy Unknown and Enemy Within, so I think it would feel cliche to bring it back a third time.  Instead, the end game of XCOM: Apocalypse might be a better fit in that rather than having one big showdown, the player engages in a series of raids intent on destroying the means by which the aliens prosecute the war.  This could all culminate in a final assault, not on the alien's main base by the player, but on XCOM headquarters by the aliens.  As the saying goes, an animal is at its most dangerous when it is wounded, scared and has no hope of escape.