ah this issue.
i cant tell you everything, but i can say what i know.
piracy is .. total. you cannot hope your game will not be pirated any more than you can hope to find a gold brick in a mcnuggets.
tbh im not totally against this, there's some ethics issues, but they are beyond the point.
if you feel that you have at hand a product (a game) which will be a market buster, by all means do invest in it; games like minecraft that have implicitly favoured piracy have made the largest amount of sales by being something so good, people *want* to pay for it, it makes them feel good to sponsor the game makers.
if on the other hand you just want a share of the pie.. well, let's just say there's a reason why pirates are so popular.
GOG made their market in another way, by providing games that are good, and that the "scene" will not bother cracking, or that were cracked a long time ago but now do not work on modern machines, and by modifying them for easy compatibility.
Unfortunately, GOG games are pirated quite heavily. The reason they make any money is that again, nostalgic, older gamers are consciously deciding to support them.
However - and i am saying this as someone who has been on both sides of the fence - don't make the game DRM free. It doesnt have to be draconic, but like they say, every little helps. Every sale matters, and the guilt factor matters as well.
There's a thought process when taking a pirated game, which can work *for* you, not just against you. Don't trivialize it by making the game something which looks and feels "completely free".
Another thing which will entice people to pay is providing something which happens *after* the game. online features, leaderboards, unique UserID and forum support, communities, will make it more appealing to the user.
F2P models are the future dont forget it. The one i play (BLR) has many people in it who have spent far more than the cost of a class-A title at launch on it, just for cosmetic content, such as character camos and taunts, because they want to SHOW the COMMUNITY that they BELONG and CARE.
If your game doesn't create the four aforementioned keywwords.. don't bother looking for a publisher.