What was the reason? Anything beyond concerns over ownership of the ideas, characters, etc. (which I presume is the boilerplate legalese)? Did they even admit to reading your letter?

In elementary school, a couple friends and I sketched out an entire game's worth of ideas for Mega Man bosses and mailed them to Capcom (this would have been 1990 or so). I remember how thick the envelope was.

I recall their response being very human, warm and encouraging, but it also included all of our original sketches, with a very direct (but kid-understandable) statement that they were obligated to return the originals to make it very clear that they were not kept and thus could not possibly be understood to be "inspiration" for anything that might be in a future game.

Funnily enough - they do actually take fan submissions for bosses - https://megaman.fandom.com/wiki/Boss_character_contest - but you’d need to do it during the development time, and probably mail into Capcom JP. Bad luck, there.

This was a very common thing media companies dealt with and still deal with. There are too many legal risks in even reading the idea. SOP is to send back the envelope sealed and with a canned response explaining that they don't accept pitches from the public.

I can't remember what the topic was, but I remember hearing a story about a company that was soliciting ideas from the public for maybe a joke book or maybe tv show plots. They got into a lot of legal hot water once they found out that the ideas weren't original and people were actually just taking them from other sources.

If anyone else knows what I am talking about, I'd like to know the name of the company.

they have to open the envelope to see what's inside - they get mail that is not ideas and they have to open it.

But I assume the people who get the mail are trained to see if the envelope contains ideas to stop reading and return the mail with the canned lawyer response.

How do they know what they are not reading if the envelope is still sealed?

Yeah, it was about the ownership of the characters that was at-issue IIRC. From memory, they said they couldn't use the characters because I made the suggestion.

When I visited the Warner Bros studios, they had a huge pile of paper in a corner, representing all the unsolicited ideas they receive.

They told us they took care to not even read the manuscripts. I don't remember if they return them unopened or destroy them, but otherwise if the ideas from the manuscript end up in one of their productions, they open themselves to legal trouble. It may happen even if it is a coincidence, so they don't want to take any chance.

Yeah, movies are kind of weird like that. If I steal your idea for a novel (but not your words), you can call me out as an asshole but you don’t have any legal recourse, but if the same thing happens with a movie, apparently it is possible to sue and actually win significant damages.

FYI, in many (most?) legal systems, you can sue anyone, for anything. To win the damages, you'll have to convince a judge or jury of said damages (or present a strong enough case to settle out of court).

Thus my saying, “and actually win”

Probably this, but despite that people keep trying - e.g. Reddit's gaming forums are full of "I made a concept for xyz!".

I mean it can work; especially for smaller studios, community members and modders are often hired to work on the game itself (I'm sure Bethesda has a lot of that, the modding community is basically free onboarding / training, but also Factorio's Space Age was mainly inspired and executed by the developer of the Space Exploration mod).