It’s a debate for another day but I presume we all know why we’re WRITING our games.
The related question is – why would anyone want to BUY our games?
A key aspect to this is – do you know your game’s unique selling point?
Another related question – with the plethora of RPGs out there, how do you know it’s unique? How do you know someone hasn’t done it before?
(Engage smug mode) I don’t have to worry about this because I’m lucky enough to have created and (co) authored a seminal game.
However, in general I’d say it doesn’t matter. You can’t buy and read every available rule set just to check your unique idea hasn’t already been used. Reasonableness comes in.
If you’re knowingly using this FATE thing everyone cracks on about, then credit it. If you think anything you use is your original creation then claim it.
Write down your USP (s) – they’re vital for back of the book blurb, marketing and – if I’m standing at a UKRPDC stand at a convention surrounded by all of our books – a list of everyone’s USPs will really help.
My Superhero games – Golden Heroes (1982) and Squadron UK (2012) – share several USPs. However, the main one is that the character generation system is perfect blend of random rolling and player design. It is, by far, the best Superhero character creation system available.
For info, my “seminal” game is Golden Heroes. I can look at games such as 1st edition Marvel Superheroes, Mutants and Masterminds and Icons and find bits where we did it first in GH. (Disengage smug mode.)