2 hours ago, jbadams said:

There are a lot of unscrupulous developers out there who will clone a game to try to cash in on its success: see for example, all the different versions of 'threes' or 'flappy bird' on the app store.

2 hours ago, jbadams said:

In summary, I don't think having your idea stolen is something you should worry about.  It is my opinion that the value you get in feedback, potential help, generated interest, etc. far outweigh any risk of idea theft.

This is a sentiment I have seen repeated fairly often when I questioned myself the same thing. I was a bit doubtful at the beginning, but I believe evidence indicate that it is really true. A good example of this perhaps are the GameDev challenges. Even for very simple and established games, the end result is slightly different for each project. 

On the other hand, convergence might still happen regardless of secrecy (think about how some themes or mechanic iterations seem to appear in batch for new games). This is natural, considering that all devs are trying to improve on what came before.

All in all, being open reduces the risky of failure in my point of view, as game devs, especially unexperienced ones, have a tendency for feature creep, getting stuck in minor details and being overly generous with the quality of our products (when we even see the games as products). 

And, why not, another post mirroring the sentiment: https://opensource.com/life/13/8/stealing-ideas 

I don't think it is a good idea to hold back information just to secure your idea.

The chance that someone sees your idea and says "this is exactly what I want with no modifications" is close to zero.

If someone thinks "hey this is a really neat idea, let me take an approach on this", he might take the idea and modify it before starting to work on it.

If you fear that other developers might steal your audience, be aware that games are not exclusive and if a game is free, you can be sure that people who are interested in the idea will take a look at your game.

You won't be able to prevent your idea from leaking to the public when you release your game and then you have the exact same problems with other devs copying the idea.

Usually they won't copy the setting and add or remove a few mechanics to make their game feel different to yours.

But the input from other developers who are trying to help you is much more valuable than the problems sharing your idea might cause.

Getting input on settings, mechanics and code is how you can improve the game by a lot.

Also be aware that most ideas are not that great on their own.

Ever heard of a game where you place blocks on top of others in a 2D environment to fill a hole?

Or a plumber walking from left to right jumping through obstacles and onto turtles?

Of course those ideas sound lame, but I don't think Tetris and Mario where that bad.

It's the result that matters.

By all means, if you don't want to talk about your game, don't talk about your game.

The downside is that nobody else can talk about aspects of your game that they don't know about. This limits the sort of sharing and coverage you are going to get. The biggest problem with most game devs is that nobody cares about your game - without some sort of buzz around it, you're unlikely to shift any copies.

The risk of anything being 'stolen' from you is basically zero. You can just decide what sort of information you want to share based on your marketing plan.

20 hours ago, SeelenGeier said:

"hey this is a really neat idea, let me take an approach on this"

And if something like this actually happens to an indie dev, like I've mentioned before, it would be an honour.

Ideas are only getting better and refined with time and involvement.

Usually the first one to implement an idea is not the one succeeding with it.

Just remember how the iPhone was just a smartphone with a very refined Interface.

Apple did nothing new and made billions with this.

In case of code, think World of Warcraft which in theory is only Ultima in 3D in the Warcraft universe.

It made Blizzard the industry giant it is now but no one really complains.

Counterstrike was just Team Deathmatch from half-life with realistic military setting and started as a simple mod...now it is an esport giant.

You can also refine your own ideas and games with a second version of your game.

Many game series best games were the second game and not the first.

Implementation > Concept

Make sure your game is playing great and the concept can be bad.

A good concept with bad gameplay is worth nothing as history shows.

The player has to have a good feeling from a game, he does not care about the overarching concept or setting.

Just think about all those awful film adaptations that had a great concept (the film) as reference and bad gameplay (just crammed something in there).

There are very few adaptation games that were actually good (Spiderman 2 was awesome ^^).