Diablo III coming May 15

You can do it if you're serious about it and willing to get a lawyer, but be aware of the obstacles.

Yeah of course it's fair use. A guide is a commentary work and it's not even close to substituting for someone buying the game. The point of copyright law is for the copyright owners to be able to make a profit -- copyright is to help encourage people to make and sell stuff. You aren't competing for sales with their game, so there's basically no way you're violating the game copyright. Just don't include video walkthroughs of the whole game (which could actually be a substitute good for buying the game).

If they've published their own game guide, just don't take any material from it and you won't be violating any copyrights on that either.

For trademark, the point is to prevent consumers from being confused about who is responsible for products, so people can build up a brand name and have a reputation they are responsible for and have control over. Guide titles like, "Ubergeek's Ultimate Unofficial Guide to Diablo 3" do not violate trademark because they do not cause any confusion about whose product this is. It's well established that you can use someone else's trademark as a substring in your product title when it's important to explaining what your product is and won't cause consumer confusion. (Similarly, "Pegasus Case for iPhone" or "Ubergeek's iPod Battery Replacement Kit" would not violate trademark.)

But, yes, as you say: being completely right doesn't prevent you having to defend yourself and spending time and money on that. (Could you recoup lawyers fees after you win? I have no idea about that.)

DISCLAIMER: I am not a lawyer. (But I have read some legal sources about this.)

I was looking forward to Diablo 3 until I heard I needed to be online to play the single player.

I generally dislike multiplayer in games and only really play single player games. I don't have much interest in multiplayer games at all really - I find other players ruin my experience and wreak the immersion. The only games I like to play multiplayer now are Minecraft and Terraria. I do occasionally play first person shooters multiplayer, but its fairly rare. In fact, the last few times it was two player split-screen modern warfare with someone who was sitting beside me.

So it should be obvious that I have nothing to gain from requiring a constant internet connection. I saw somewhere that Blizzard were saying they are requiring this so you can migrate characters between single and multiplayer without the risk of players cheating - this is just not a use case for me at all because I will never migrate my single player character to multiplayer. I'd much rather have an option to make a single player only character that doesn't require constant internet.

So besides not wanting or needing that feature, why else do I not want to be forced to be online all the time? I don't usually play games on a laptop while traveling, so that doesn't apply to me, but while I do have reasonably fast internet, over the past year I have had random disconnections (mostly due to issues with wifi, including wireless adapter breaking and wireless interference) and the occasional outage. Usually when my internet isn't working, since I use it for work, I will fire up a game for a little while until the internet is working again or until I feel like fixing it. I've already been bitten by steam a few times so I now default to leaving it in offline mode, only going online when I want to check for updates or buy/install a game. In the past three months, I've been irritated more than a handful times that I couldn't play certain games because I didn't have an internet connection for whatever reason. While this alone wouldn't put me off buying a game, coupled with my overall distaste for multiplayer, I don't see why I should have to pay (in frustration) for being online when I play a single player game.

So, for those reasons, I will never buy Diablo 3, even though I was looking forward to it.

Different taxes and laws.

In EU, Apple hardware or games are often priced at the same amount as in the US, but in Euros, not $. No wonder: the price includes value-added tax (20% or so, depending on the country) and the seller has to account for significantly stricter consumer protection laws. For example, the standard warranty period is one year in the US; in my country, the law requires two years; that's got to affect the price.

it always has been click and hold.