It's a fantasy role-playing game.

DM: You are Tiberius Stormwind, a dragonborn sorcerer . You are the member of the famous group of adventurers. Previously, The party, after essentially forcing this individual to reveal themself, the rakshasa fled through a tunnel underneath its room into a long subterranean tunnel fraught with traps that were set to protect it. The party managed to avoid these rather deftly until the steady decline of the hallway, combined with the increasing moisture and scent of refuse, caused a slick surface and our fantastic cleric, Brother Kash, Kashaw, slipped and fell down.
DM: It's a giant cylindrical-- it looks like it was once a cistern that has been turned into some sort of a refuse--
Player: Is there a roof?
DM: From what you can see? Roll a perception check.
Player: What do I use?
DM: Perception. It's a skill. You don't use it very often.
Player: 15. No, 14.
DM: As far as you can see, it goes up maybe 30 or so feet beyond the radius of your Light spell and fades into darkness. You have no idea if there's a ceiling or end to it or how far it would be if there was one.
Player: Okay. Well, I've got one right next to me, right?
DM: You do.
Player: I'm going to put out my hand and I'm going to do a Firebolt right next to that one.
DM: Okay. Go ahead and roll to attack with disadvantage.
Player: Why, are they on me?
DM: Yeah, they're right up against you. Ranged attacks, when you're in melee with the target, it's at disadvantage.
Player: Oh, right. Well, then I'm going to not do that. I'm going to cast Obelisk of Stone and then quicken spell and then I'm going to do a Firebolt. That's what I'm going to do.
DM: Okay.
