Walls enemies can see through but not shoot through.

I was wondering if it was possible to do this in boom format.

A self-referencing sector (formerly also called a crystal sector) allows the player to see through it, but nobody can shoot through it. To allow the monsters to see the player, you need a 1-unit gap either on bottom, on the side, or maybe in the middle. Only a super-lucky hitscan attack can get through that gap.

I know you said Boom but in UDMF it's as simple as checking the flag to block hitscan attacks and projectiles but keep block monster line of sight unchecked. Unfortunately it also blocks player hitscans and projectiles since GZDB doesn't have the option to only block monster attacks.

3 hours ago, Nevander said:

I know you said Boom but in UDMF it's as simple as checking the flag to block hitscan attacks and projectiles but keep block monster line of sight unchecked. Unfortunately it also blocks player hitscans and projectiles since GZDB doesn't have the option to only block monster attacks.

Thanks for the info! But I don't map in UDMF. I map in Boom.

Couldn't you just have a super low ceiling that enemies can technically see through but cant attack through? Like a pixel or two in height, add a midtex to complete the look?