4. You may distribute machine-executable forms of the Software or machine-executable forms of modified versions of the Software, provided that you meet these restrictions:
a. You must include this license document in the distribution.
b. You must ensure that all recipients of the machine-executable forms are also able to receive the complete machine-readable source code to the distributed Software, including all modifications, without any charge beyond the costs of data transfer, and place prominent notices in the distribution explaining this.
c. You must ensure that all modifications included in the machine-executable forms are available under the terms of this license.
Translation: any binaries you create must be accompanied by the source code used to compile them. Additionally, if you modified the source code, it must comply with the same section that relates to patches:
This means that any modifications you make to the client become the property of Radu, and he has the right to add them to the official client.
3. You may make modifications to the Software and distribute your modifications, in a form that is separate from the Software, such as patches. The following restrictions apply to modifications:
a. Modifications must not alter or remove any copyright notices in the Software.
b. When modifications to the Software are released under this license, a non-exclusive royalty-free right is granted to the initial developer of the Software to distribute your modification in future versions of the Software provided such versions remain available under these terms in addition to any other license(s) of the initial developer.
c. You must cause the modified files to carry prominent notices stating that you changed the files and the date of any change.
The following restrictions section of the license is the most clear:
The one that affects the most people is #4. Any modified version of the client that connects to the server is in violation of the license.
1. You are not allowed to use the Binary Data that comes with the Official Eternal Lands Client without our prior approval.
2. You may not distribute our Binary Data in your modified versions, without our approval.
3. You may not use our Trademarks (such as Eternal Lands) in modifed version
s, without our approval. You can (and must) add a notice stating that the code is a Modified Version of the the Eternal Lands Official Client.
4. You may not use modified versions to connect to the Eternal Lands server, without our approval.
In order to get approval for connecting to the server with a modified client, you should notify the developers in the Programming forum that you want to begin work on something. It could also save you time, if there is someone else already working on a similar modification or the modification will not be allowed. People who are already active in development and have been submitting patches do not need to worry about this, you have permission.
An exception to the modified clients rule is bots, which must follow the rules here: