

It has the same game engine, but the difficulty and map size are increased, making it much lengthier. TFTD has the look of a "reskin" or an expansion, but is an actual sequel to UFO Defense. Now, they're upset that humanity had the audacity to deny their space-borne brethren the rite of conquest, so they're picking up where the war left off.

Turns out they visited Earth a long time ago, and then never left due to crash-landing. After their last failed bid to invade, the aliens on Cydonia sent a message.to the oceans of Earth. X-COM: Terror from the Deep is the '95 follow-up to X-COM: UFO Defense (or Enemy Unknown, depending on your nationality) which tries to change as little as possible.
