In C# XNA/Monogame, will be open-source, likely using GitHub.
Yes I have the necessary experience with creating games, it will use my private engine "SharpXNA", Multiplayer/Networking will be done using Lidgren, by a wrapper in my engine to make it better/easier.
Not entirely sure when I will begin, should be some time relatively soon.
[mod edit: links removed]
This post will be updated over time, as this is just a brief draft for now.
Unfortunately this appears to be copyright infringement, which is not allowed here.
While copyright law varies from location to location, in general a project like this cannot be based on the same art, story, music, characters or world as appear in someone else's game. Note that whether your game is going to be free or not doesn't really change this, though making money from copyright infringement can open you up to harsher penalties.
There are a few reasons for this. One reason is the makers of Hotline Miami could intend to release multi-player at some point in the future, and your project could create confusion in potential customer's minds. Another is that if you spent thousands or millions of dollars developing a brand new game with unique characters, story, etc, you would have full control of that experience and know that if anyone else comes along and tries to use your ideas in ways that you do not like you can stop them.
If the current owners of the copyright discover your project, they can choose to tell you to stop. It would be devastating for this to happen if you invest months or years into this project only to find a "cease and desist" letter causes some or all of that work to be pointless.
I am not a legal expert, but my understanding is that there is nothing preventing you from writing a similar gameplay, so it might be possible to create a similar experience but set in a new world (e.g. some prisoners escaping from a medieval castle, infiltrating an alien base in a far distant galaxy). A lawyer would be able to guide you as to how safe you from a lawsuit for any variants you come up with.
