When I was learning Deep RL, I edged on what could be done through OpenAI gym, or self-made environments, I decided to begin working with MuJoCo.

But for an undergrad student from a developing country, the fees were extremely high.

So, I just didn't go forward with Deep RL much. I dabbled for a while and tried using PyBullet. Did not go that well.

Also thought about creating custom environments in Unity and then apply Deep RL in there. But it took too much effort.

Creating a complex enough environment and getting used to it were, in themselves- full projects that took long term commitment.

As a result, I did not learn much Deep RL to be able to apply it to complex, real-world-like scenarios.

I think that it is going to change.

I am excited about books, blogs, and videos that are going to be created as MuJoCo is open-sourced and available for free.

I, personally, will get back into Deep RL the next opportunity I get.