We don't copy codes/ graphics/ sounds from other games. ZDefense uses a Open Source Android Game Engine - AndEngine. We did some enhancement to that Engine and also send the modification back to Nicolas - the author of AndEngine.
We totally have no affiliation with the creators of hex defense. As I know Hex Defense is created by 3 MIT students. We are a game studio from China.
When people first take a look on ZDefense, they might find it looks similar to Hex Defense. That is just because Hex Defense is well-known but ZDefense is a new comer.
Actually there are many Tower Defense Games that use Hexagon cells including Defensoid / Vector Defense / Hex Defense and ZDefense. Defensoid was released 3-6 months
earlier than Hex Defense. All these games are inspired by the famous iOS game GeoDefense Swarm.
We add lots of unique features that are not found on Hex Defense even GeoDefense Swarm including Space Gate/ Space Tunnel/ Extreme Mode/ Map Editor and Free Maps downloading / Replay and many other small features.
The levels are also more fun than those of Hex Defense. ZDefense has 50+ levels much more than that of Hex Defense. We carefully design every levels, players must think a different strategy to pass different levels. Generally each level would takes 20+ minutes to a few hours to pass it. We have a forum that players can share their success screen's screen shot to help other players to pass that level if they are blocked. Hex Defense's level design is not very good on my opinion. Hex Defense use a very cool background music. So they make creeps come out by a fixed sequence to let it match the rhythm of the music. That hurts the diverse of levels. Players just need to use the same towers sequence to defense. I just spend 2-3 hours to pass all Hex Defense levels. ZDefense also support more towers, more mode, bigger maps. Hex Defense also has its advantage. The bosses on Hex Defense is very cool.
Both ZDefense and Hex Defense are good tower games IMO. Hex Defense is good for the players who don't play Tower Defense a lot and ZDefense is suitable for hardcore TD players who like new challenging.
Now let's talk on permission.
The permission to discover known account is needed by OpenFeint Leader Board.
OpenFeint uses that permission to autofill the email field when users sign up OpenFeint.
I quote the following text from OpenFeint Document.
"To allow OpenFeint to retrieve the logged-in user's email address from Phone SDK version 5 or above so that the user does not have to type the email address in when creating an account, add the following to the AndroidManifest.xml:
OpenFeint is a very famous mobile game social SDK that providing Leader Board / Achievements and other features on iOS and Android platform. Nearly 7000 games have integrated it and more than 100M users have registered on it. It is definitely NOT a spyware. If you don't feel comfortable about it. you just don't sign up. If you have sign up, you can modify the Email Address if you don't want use the email of your android account.
I am sorry that I don't clarify it on the game's description. OpenFeint was integrated into ZDefense nearly 2 months ago on version 1.2. On both Android Market and Amazon AppStore, nobody complaints about it. So I didn't know it would be a big concern.
We just want to make good games.