Your best mapping gotchas/errors
(A Trigger was missplaced)
So, try again ^^
in a map project i've abandoned (project basement, which you can download in wip maps)
i have a custom underground style faithplate, and one time it just kept launching for no reason. turns out the catapult trigger was touching the dynamic props that it was made out of and kept firing. 
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Im blue, a Clean Christian Furry with Autism.
Sometimes i make triggers and forget about to tick the Flag "physics Objects", then i spend so much time to figure out why the trigger doesnt send any output. . _.
One time, I was making a map with a cube dropper (So unique). When the dropper opened, the cube only stayed in place as if the dropper never opened, but it did indeed open. I opened the instance to make sure that the collisions were set correct, and experimented with a bunch of other droppers. None of them worked. I then moved my camera back in the 3D veiw, and saw I had an invisible brush below. -_-
Musical website Moddb
To be honest, I think I've made too many of these kind of errors to even be able to keep track of them all. It's always the stupid stuff that causes problems, like forgetting to give something an input to enable it, or forgetting to change a file path, forgetting to change keyvalues, or compiling without un-hiding stuff.
EDIT: I've done one just now - I was using a trigger_weapon_strip and couldn't figure out why there was a portal gun model in the spawn elevator. Turns out 'Kill Weapon' was turned off.
A funny thing is, in English, GLaDOS says (for example) "You're great", and she speaks to the coop bots.
But in German you can hear, if she speaks to one person, or to two persons, because she would say to the coop bots "Ihr seit gut". To chell she would say "Du bist gut".
Now many people use some voice lines, from the coop. Because in english she always says "You", But when German people play that, it just sounds weird.
Grammar is not my best language, hope you understand what i mean 
For example, in "The Winter Testing Initiative", in the german version, is Glados talking to more persons, maybe also in other languages ^^
But in German you can hear, if she speaks to one person, or to two persons, because she would say to the coop bots "Ihr seit gut". To chell she would say "Du bist gut".
Now many people use some voice lines, from the coop. Because in english she always says "You", But when German people play that, it just sounds weird.
Grammar is not my best language, hope you understand what i mean
For example, in "The Winter Testing Initiative", in the german version, is Glados talking to more persons, maybe also in other languages ^^
Yes, it's a common thing; in English "you" can be singular and plural; whereas in a lot of other languages it's a different word for either version; with it's own grammar! So in order to get the best experience; just change portal to English; you might even learn something from it if English isn't your native language. If you have trouble with listening and understanding; you can also turn on the captions 
Understanding was never a problem for me, but Grammar in writing, thats a little bit difficult for me
But im learning it ^^
On my WIP Map I dropped a turret down my bottomless pit on the map...
It didn't get destroyed.
PLEASE DON'T LOOK AT MY POSTS FROM 2013
THEY ARE UGLY AND HIDEOUS