Meaningful choice
Also said as Meaningful play, Real consequences
A choice whose result you can see and which changes what comes later. Katie Salen and Eric Zimmerman's Rules of Play asks for both: the outcome must be discernible and integrated into the larger game.
A choice nothing follows from is a choice players soon stop caring about, and if the result is hidden it may as well not exist. Both waste the work that went into the choice.
Say it
“If siding with the guild changes only one line of dialogue, cut the choice. Either the guild closes its shops to you afterwards, or we do not ask.”
Where you’ve seen it
In Mass Effect, a mission on Virmire makes you save one of two squad members. The other is gone for the rest of the series, and it shapes who is beside you from then on.
Not to be confused with illusion of choice
An illusion of choice feels meaningful the first time and leads back to the same place. It is cheap to build, and players notice on a second playthrough.