Can you prevent the player from turning around (vanilla)

You can't.

You can with ACS. Use SetPlayerProperty with PROP_TOTALLYFROZEN and the only control they can use is the Use key. To cancel the player's current momentum, use Thing_Stop. You might also want to use SetActorProperty with APROP_Invulnerable as well.

You could have an animated wall texture play a "cutscene" I suppose using lots of frames. You could even have a long story with scrolling text with clever use of midtextures feature the story text combined with lowering floors, but ZDoom is still clearly better to use for cutscenes.

@bzzrak If you really want this wad to remain vanilla, I say just do it as you had planned and if the player for whatever bizarre reason wants to turn their back to the cutscene, I guess that's their own loss? It could still be a cool thing to see, I can't think of anyone attempting a cutscene in vanilla before off the top of my head.

4 minutes ago, Empyre said:

You can with ACS. Use SetPlayerProperty with PROP_TOTALLYFROZEN and the only control they can use is the Use key. To cancel the player's current momentum, use Thing_Stop. You might also want to use SetActorProperty with APROP_Invulnerable as well.

Yeah....only with ACS. In plain vanilla, you can't.

https://zdoom.org/wiki/Using_ACS_in_Doom-format_maps

Can you even do cut scenes in vanilla?