It is implied that PCs are exceptional, and able to "tune in" to alternate universe selves with different powers (Alpha Mutations), but the general impression is that the world is relatively stable.
Mind you, there's nothing saying you can't have morphing terrain.
Now there is terrain that will increase the odds of Alpha Flux (Beta-moss makes alpha-flux occur on a 5 or less) and there are monsters that cause Alpha-Flux to increase with their aura (Blaash/Gama Moth).
So to your point, about Terrain Morphing/Alpha-fluxing. I would say a reversed mechanic could certainly work, any-time the DM rolls a 1 the terrain changes.
There is a good sized list of some odd terrain on pages 98 and 99 - one is called the Gamma Flux Zone where "reality" has not yet stabilized, but the terrain does not change, only the odds of the PCs suffering an Alpha Flux on a 5 or less.
Theta Flux Event * At-Will
Trigger: A creature rolls a natural 1 on any d20 check while within a Theta Flux Zone.
Effect (Opportunity Action): Each unoccupied space adjacent to the triggering creature (including blocking terrain) experiences Theta Flux until the end of the triggering creature's next turn. Roll 1d8 for the effect:
1 - The squares become normal terrain.
2 - The squares become difficult terrain.
3 - The squares become blocking terrain.
4 - The squares become challenging terrain, requiring a moderate Athletics or Acrobatics check to move through. On a failed check, a creature is slowed until the start of its next.
5 - The squares become hindering terrain that inflicts 5 points of radiation and electricity damage on any creature entering it or starting their turn within it.
6 - The squares become lightly obscured.
7 - The squares become heavily obscured.
8 - The squares become a time-space fracture (see page 99 of the D&D Gamma World Rulebook).
Special: The triggering creature does not experience an Alpha flux event.
Now that I like. Well done Oraibi.
Theta Flux Zone: Similar to a Gamma Flux Zone, a Theta Flux Zone is a region of Gamma Terra where the worldlines still fluctuate. Within a Theta Flux Zone, creatures are safe from Alpha flux but the terrain is malleable and reacts to their presence. The following triggered action applies whenever any creature is within a Theta Flux Zone:
Theta Flux Event * At-Will
Trigger: A creature rolls a natural 1 on any d20 check while within a Theta Flux Zone.
Effect (Opportunity Action): Each unoccupied space adjacent to the triggering creature (including blocking terrain) experiences Theta Flux until the end of the triggering creature's next turn. Roll 1d8 for the effect:
1 - The squares become normal terrain.
2 - The squares become difficult terrain.
3 - The squares become blocking terrain.
4 - The squares become challenging terrain, requiring a moderate Athletics or Acrobatics check to move through. On a failed check, a creature is slowed until the start of its next.
5 - The squares become hindering terrain that inflicts 5 points of radiation and electricity damage on any creature entering it or starting their turn within it.
6 - The squares become lightly obscured.
7 - The squares become heavily obscured.
8 - The squares become a time-space fracture (see page 99 of the D&D Gamma World Rulebook).
Special: The triggering creature does not experience an Alpha flux event.
That is what I'm talking about, thanks.
I think it just gave me an idea for another origin as well!cut and paste, credit given, published, formatted a bit. fantastic idea.