Have you ever played a Sven map where you had to retrieve a disk or key and when you go over it, it disappears and text pops up saying you found it? Ill teach you that and it's very easy to make.
First make your disk,key,etc. Then create it as a "func_wall_toggle" entity then give it a target name. After that, place a block just a bit bigger than the actual disk,key,etc around it and make sure to use the AAATRIGGER texture when you place it. Make that AAATRIGGER a "trigger_once" and have the AAA target the disk,key,etc.
That would make it disappear. Now if you want it have some text pop up, make a "game_text" entity and set it up. MAKE SURE to give the "game_text" the same name as the disk,key,etc. That will make it seem like you picked the disk,key,etc up and told you found it.
Now, that you picked up the disk,key,etc now you want it to open a door or what ever. just create your door and have it the same name as the disk,key,etc and when you pick it up it will open the door.
If it doesn't work then post a reply saying it doesn't work or just post feedback idc.
