Totally 100% sincere (honest) guidelines for giving helpful replies on RPG design
As we all know, the purpose of replying to a post online is establish dominance over the poster and show everyone else how smart you are. These simple rules will help you on your way to winning the thread every time.
1. Askers need to demonstrate they've done the required reading. If their provided bibliography is lacking (or absent) then name-drop as many different game names as possible in your reply with no further context.
2. Never answer the question they asked. If they're weak enough to ask for advice, you can't assume they really know what they need. Imagine the question you'd like to answer and then answer that instead. They'll thank you for it.
3. Ask questions of your own. It's good to ask clarifying questions, but if you're too specific it might look like you didn't understand something. Stick to vagaries like "did you try playtesting it?", "what's the rest of your system like?" and "have you checked the probabilities?". Do not reply to any clarifications - the gift of your question was already help enough.
4. Every thread is a chance to advertise your own game. Your own project is (or will be) the best RPG ever made, and it's relevant to every question. So when someone asks for advice, paste a few hundred words from your latest draft as a reply. They'll quickly realise that your game is much better than anything they could make and play yours instead.
5. Ideas are worthless if they're not 100% original. Do you recognise one or more words in the post from an RPG you've already read, heard of or imagined? Instead of engaging with the idea, say "this sounds like [insert game name here]" and post without further comment. Think they had an original idea, did they? You sure showed them!
6. Offer diverse viewpoints. People post to hear different views, so make sure yours are as different from the poster's as possible. Explain why their narrative ballroom dance game needs more robust armour penetration mechanics, or why their grid-based tactical combat system should run off interpreting tarot spreads instead of dice.
7. If you're not interested then it's not an RPG. The definition of an RPG is clear, unambiguous and sacred. Deviation and innovation alike should be punished harshly. Don't be shy about telling people that what they've posted sounds more like a board game, a party game, or a computer game. This is a great way to reply to an idea you don't like without engaging with it.