With a few noteworthy exceptions, most games tend to have a fairly homogeneous progression, usually going from lush green grasslands and becoming progressively more wild, desert, jungle, and usually ending with freezing cold, winter perhaps, snowy tundra, or soaring mountain range. Some examples:
Diablo 2 progresses from the temperate plains around the rogue encampment, straight into the desert of Lut Gholein, forests of Kurast, and finally hell itself. The expansion then takes the hero to the barbarous wastes of Harrogath, a land filled with massive, destructive beasts and hellspawn.
Borderlands is almost exclusively deserts and salt flats, being the more common terrain on Pandora. The finale however takes our Vault Hunter to a snow-capped mountain in the Eridium Highlands.
Bastions journey leads the Kid from the ruins of his old town through the drifting chunks of Jawson’s Bog, forests and jungles, ending in the ice blocks of Urzendra Gate, Zulten’s Hollow and the Tazal Terminals, dripping with icicles.
Castle Crashers, Titan Quest, the masterpiece edition of Myst, Grim Fandango when you think about it, Skyrim’s fairly snowy all over but the difference from Helgen to the Throat is a marked difference, Pokemon Gold/Silver ends on Mt. Silver, and I’m sure if you think on it you’ve already conjured a few examples yourself. Why do so many game designers take their story along this path?
There’s a literary device known as Pathetic Fallacy, you may be familiar with it. The sun shines on happy days, it rains when everything’s sad, it’s tragic, but some people still do it, and if it’s done well enough you’d never even notice it was happening. The same thing can also apply to the seasons, they follow a fairly natural progression with all the metaphors to go with them, spring is a time of rebirth and new beginnings; summer is filled with life, growth and joy; autumn is a period of decay, when everything is undone and falls into decline; finally winter is the season of darkness, and death.
The progression of a game follows a like-for-like path, and often the terrain and weather reflect it. A game usually begins with the birth of a hero, the call to action that takes the normal person into a story. The action builds, intrigue rises, suspense and activity grows, driving the hero to develop and achieve things he/she never thought themselves capable of. Finally the real conflict is ahead, seemingly insurmountable, friends fall behind, the world crumbles, the hero is faced with an impossible decision or heartbreaking revelation. They overcome at last to stand before the end, victory or defeat, life or death, pivoting on a single moment.
A less heroic analogy, a decline in weather follows the decline of Prince Arthas in Warcraft 3, from the young hero of springtime, and the madness he pursues takes him into winters death, which then follows him everywhere he goes.
Keep your eyes peeled for this particular quirk of media, and how weather can influence emotions as part of narrative, and particularly look at how it can change your perspective on an area. It may not be the very last segments of the game, occasionally they are the very beginning (Metal Gear Solid, Borderlands 2, Rise of the Tomb Raider), but they’re frequently pivotal, memorable, tough, or some mixture of all three. If you’ve ever felt daunted at the sight of snow then you’ve already fallen victim to pathetic fallacy.