The targeting line does say a point you can see, so not around corners, but because it doesn’t specifically target creatures, it should hit invisible enemies just as well if they are in the blast radius.
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Anything is edible if you try hard enough!
I am a swimmer. If you see me running, you should run too, because it means something horrible is chasing me.
our group is having an issue on this spell being able to cast to unseen or around the corner out of sights any thoughts
The AOE of fireball "goes around corners", so you can cast the spell on a point you can see and targets you can't see which are in total cover from the point but for whom there's an unobstructed path entirely within the radius of the spell that can reach the target will suffer damage. So you can't hook the spell around a corner, but you can use it to murder people around a corner, potentially even by targeting a space next to a wall, rather than next to where the wall isn't.
The issue is the spell itself does not say line of sight and some of my friends are arguing that point
It doesn't have to, the spellcasting rules do that already.
A Clear Path to the Target
To target something, you must have a clear path to it, so it can’t be behind total cover.
If you place an area of effect at a point that you can’t see and an obstruction, such as a wall, is between you and that point, the point of origin comes into being on the near side of that obstruction.
our group is having an issue on this spell being able to cast to unseen or around the corner out of sights any thoughts
The targeting line does say a point you can see, so not around corners, but because it doesn’t specifically target creatures, it should hit invisible enemies just as well if they are in the blast radius.
Anything is edible if you try hard enough!
I am a swimmer. If you see me running, you should run too, because it means something horrible is chasing me.
The point of origin has to be a point you can see, then the effect can hit unseen areas/targets.
The AOE of fireball "goes around corners", so you can cast the spell on a point you can see and targets you can't see which are in total cover from the point but for whom there's an unobstructed path entirely within the radius of the spell that can reach the target will suffer damage. So you can't hook the spell around a corner, but you can use it to murder people around a corner, potentially even by targeting a space next to a wall, rather than next to where the wall isn't.
The issue is the spell itself does not say line of sight and some of my friends are arguing that point
It doesn't have to, the spellcasting rules do that already.
As Thezzaruz pointed out, that is already a general rule that applies to all spells unless the spell specifically says otherwise.
Here is the rule source: https://www.dndbeyond.com/sources/basic-rules/spellcasting#Targets