I think there may be a small language barrier . I think people seem be annoyed because following sentence means (probably for most people who read that) that you claim to have started working only 2 days ago for this game:
This obviously isn’t the case as you already have a work in progress thread about the game:
https://forums.unrealengine/showthread.php?84717-Escape-the-Asylum
Also, I’m not talking from others behalf, but I’m pretty sure that game jams are not the right place to advertise your existing product. If you want to give a demo of the gameplay, you could provide that in your WIP-thread instead 
That being said, just to make things clear, posted earlier this:
So technically, things could be just fine although I’d think that statement was about more of using your existing artwork etc for the game jam and not about extending existing game as that’s not really what game jams are about. I don’t think anyone is trying to be mean so don’t worry about that I wish the best of luck on your project myself! All in all, I think the negative response you’ve gotten has only been because people have understood that you’ve claimed to start working on the game 2 days ago, that’s probably all there is to it.
As a side note, I personally think mixing prizes for event like game jam with such vague rules and lack of their enforcement (some art competitions expect to post wip screenshots during the event) is one reason why some people have gotten nervous about the competing entries as it would be so easy to cheat and get into position to compete for the top entries. And this certainly shouldn’t be what game jams are about at all as instead of competition, we should be supporting each others.