There were two games which I almost bought. I made an offer to the first game’s author: “Let me translate your game to Finnish and give me a free copy”. I could not get a reply and was about to email: “how about a discount?” but I didn’t. I waited. The next day the author accepted the offer and gave me the registration key. Notice: he could have said “no” or suggest a discount – and I would have accepted. He lost money.
The other gamer was even more interesting: I told them a couple of hints on how to improve their game and they said “thanks”. Few minutes later I got another post from them stating: “oh, and here’s the reg key”. Why did they give me the registration key for free? I would have bought the game (it was only $9.95).
Don’t give your game for free. Save discounts for very rare exceptions. But a rule of thumb: don’t give your game for free. Hints, tips, news, mini-games are okay to give for free… but don’t give your game for free.