Question: How do you make it so that when you pick up a key, it doesn't open the door its supposed to be for, but when you go up to the door, it opens up every single time. Look under if you dont understand.

Ok, theres a door, theres you, and a key. The door wont open without a key, and theres a key there. You grab the key and then use it to unlock the door and the door opens any time you interact with it. How does one make it so?

Is it like a system of triggers? or a multi_manager? I can't get this down because mapping for a dead mod is kind of hard and annoying (attempted a few times, made a stupid map, made another stupid map, and now im making a map with sharks and ants because there are no maps have sharks and ants. Yes, Sharks and Ants are MONSTER ENTITIES, not just models.)

I wouldn't know exactly, but it should work a bit like this.

Having a trigger_once box around the key which targets a multi_manager, the multi_manager targets the key which would be a func_wall_toggle(to have it disappear once picked up.),and an entry to target the door, which can be toggled to be locked or unlocked, there's probably some flags for it to be locked by default on map start.

multi_manager is used to target multiple entities at once, also if you want a timed execute of multiple entities, you would use that too. make sure to turn off smart edit before trying to edit it, if you haven't used them before.

Is this using the Half-Life FGD or are you using a new FGD? Give me more details.

Stoned:
Its an old .fgd file from '08 when it was last updated. I never use the half-life.fgd and i don't have it.

But cartman's response worked. Figured they had to be func_wall_toggles.

But now I'm clueless on one thing:
How do you have a button be locked until you get a keycard/key for it to be unlocked?

it's probably something similar, is there any options or flags to have it locked by default?

I don't think so.

Maps in Sven Coop have buttons that respond 'Access Denied', until you get something, and then its 'Access Granted'