Game design decisions

Now as it stands I am not very sure what game I am making in particular but I do have a few options ahead of me now I have got other business out the way!

I could use Unity with other languages to build my game since it supports each, I could use Java with Eclipse...

Most of all I am currently leaning towards flash, and taking an earlier project and making it better and fuller as a fully operational game.

I don't have a lot of time.
I will make a mock up of a HTML simple game and see how it goes first and if that doesn't work, I am going with flash.

Now to think up how I want my game to run!

Design is always time consuming for me.