So, I like to think I'm a pretty honest person, at least insofar as I try not to engage in activities that I know will make other people feel robbed or supplanted. I've been MU* ing on and off for just over half of my life, and RPing in general (starting with tabletop D&D) since I was 9. Throughout I've found things I like about this hobby/community, things I don't, and eventually become disenchanted with mostly every game I've played. They all had flaws, all had things I felt could be done better, which I think is a normal expectation to have out of anything. But eventually I arrived at the conclusion that I'll never be satisfied with these half-perfect games, and that what I need is to create my own idea of exactly what an ideal MU* should be, for myself.
This isn't the first time I've ruminated on this, and it's actually why I originally sought to become staff on several games I've played. I've learned a lot, gotten ideas here and there, some of them being about how my game should be done differently to any other game before, but also some more humble moments of, 'Hey, I like that. This idea here that this person has implemented, it's a good one. It solves a lot of the problems I've seen other games have.' Some of these ideas from other games I'd like to use.
As a more innocent example: event scheduling, which is common to MUSHes. MUDs don't have this because they do everything spontaneously, but I actually think that telling casuals, 'Hey, I know you can't afford to spend all day loitering on this game waiting for something to happen, but if you log in at this hour on this day, we're gonna have some guaranteed fun for you to participate in.' That's great. Much better than wiling hours away on MUDs waiting for something to happen or pointlessly hoping that players will be more proactive when they mostly just aren't wired that way.
Less innocent example: I really liked HavenRPG's dream-oriented RP. Some of my best scenes on that game (which, being obsessive, I tend to log so that I can review objectively years later) involved the creation of nightmares for other players to experience using my evil supernatural character, invading their dreams to convey a message, and generally being able to create this fun surreal playground for absurd RP that obviously can't/shouldn't happen when the characters are awake. That's something I'd definitely like to implement if I ever made my own game.
With a collection of less innocent 'borrowed ideas' from various games though, I start to wonder at which point my intentions would be crossing a line. I've heard the sayings that ideas are cheap and that there's no such thing as a truly original work, but at the same time, I myself can't help but feel irritated when someone else borrows my ideas and receives credit for it, intentionally or otherwise. I'm sure we all have that friend who repeats jokes you yourself were the one to tell them years ago, because our brains are stupid and people can actually forget that the source of something they thought was original was actually gotten elsewhere. This can happen on a more serious, consequential scale, and since I don't like it when I'm on the receiving end of it, I'm wary of putting anyone else in that same position.
Preempting an unintended line to this discussion, because I know we have some actual lawyers here — sup @Ganymede — my question isn't about what's legally considered theft of intellectual property, but rather how people feel about the line ethically, emotionally or practically. If someone was going to use ideas you know you came up with (especially if they themselves could still recall where they got the idea from), what would you expect from them? I know that I'd probably like to list credit where it's due with some kind of acknowledgements page, such as 'thanks to HavenRPG for inspiring idea X, Legend of the Green Dragon for inspiring idea Y, and @SkinnyThicket for the innovative mapping/exploration system', but I'm interested to hear thoughts from developers/players here about the practice of idea-borrowing in general.