You can invoke aspects for a bonus to a roll (page XX) and compel them to create a complication (page XX). But even when those aren’t in play, aspects still affect the narrative. When you have that flesh-wrapped monstrosity Pinned in a Hydraulic Press, that is true. It can’t do much stuck in there, and it’s not getting out easy.

In essence, “aspects are always true” means that aspects can grant or withdraw permission for what can happen in the story (they can also affect difficulty: see page XX). If the aforementioned monstrosity is Pinned, the GM (and everyone else) has to respect that. The creature has lost permission to move until something happens which removes that aspect, either a successful overcome (which itself might require a justifying aspect like Superhuman Strength) or someone foolishly reversing the press. Similarly, if you have Cybernetically Enhanced Legs, you’ve arguably gained permission to leap over walls in a single bound without even having to roll for it.

That’s not to say you can create any aspect you want and use its truth like a club. Aspects grant a lot of power to shape the story, yes, but with that power comes the responsibility to play within the story’s constraints. Aspects have to line up with the table’s sense of what actually passes muster. If an aspect doesn’t pass the sniff test, it needs to be reworded.

Sure, you might like to use create an advantage to inflict the aspect Dismembered on that fungal super-soldier, but that clearly steps on the toes of the attack action, and besides, it takes a bit more work to lop her arm off than that (could work as a consequence, though—see the next page). You might say you’re the World’s Best Shot, but you’ll need to back that up with your skills. And as much as you’d like to make yourself Bulletproof, removing permission for someone to use small arms fire to harm you, that is unlikely to fly unless the game you’re playing involves using aspects-as-superpowers.