Summary
You should read the full terms and conditions but here is a quick summary of some important points to help guide you - the full terms and conditions still apply though.

Do not redistribute our games or any alterations of our games or game files.
You may develop tools, plug-ins and services as long as they do not seem official or approved by us, such as by using our logos. Do not make commercial use of anything we've made without our permission.
please review the binding arbitration agreement and class action waiver that is part of these terms and conditions. Under the agreement, we both agree to use a neutral arbitrator to decide any individual claims that may arise and thus agree to waive our rights to bring individual claims in court for consideration by a judge or jury. We also agree that class action lawsuits and class-wide arbitrations are not allowed under the terms of the agreement.
We are trying to be open, honest and trusting with the hope that you hold us in the same regard.
Our games each have their own end user license agreements which explain how our games can be used.