Why would a company want to integrate BTC to their game when they can just use their own currency?
Xbox Points, Fifa Coins, WoW GOLD etc... They take your money and convert it into a currency which you can NEVER SPEND ANYWHERE ELSE. That is the most important factor. They don't want you spending that money anywhere else. Using BTC would be the exact opposite of what they are trying to achieve. If you think any company is gonna allow you to withdraw in-game currency to pay for your car you are mad. That is exactly what they fight against.
Now 'Gaming' on the other hand (I mean gambling), Yes BTC could be huge. Right now many companies are struggling with anti-gambling regulation around the world. Using Bitcoin they can subvert that process.
They monetize their game (provided for free) with Bitcoin. They sell virtual items directly to the player for bitcoin. They attract players by offering the possibility to "earn" money by searching for various virtual items. Of course, the majority are going to simply pay to win (this assumption is drawn from years of gaming experience). It basically functions like a casino where the house always has the advantage and the player feels like they can win money by playing.
A lot of popular games have gone down this route (free games monetized through in game purchases). It's a nice system. It also happens to mesh with Bitcoin quite well.
I believe you're referring to microtransactions which have become a prevailing trend in gaming (I'm referring to video games) much to the chagrin of gamers (but that's a whole other topic). And yes, the concept would mesh extremely well with bitcoin IMO and it seems Zynga agrees.