Do we go with video game software or with industrial? We need some criteria for fixing on our first simulation software. How important is the interactivity of the simulated robotics upon the landscape? What software is best for the AI to update as it alters the terrain? The best software for detailed robotics the AI can begin altering? What is the best simulation that can ignore the graphic output or do we need standard graphic output for the motivation and visualizing of those who are constructing the real world robotics?
Some of the stupid questions that may be moot as we may be able to take any of the many choices we have today and make it work our magic. Most likely when such a choice comes into play the solution is what one or more of the users is already most familiar with. Perhaps the most important criteria is that the code be open source so we can modify our specialty needs into it?