the most important is to make it as easily and quickly accesible
as possible.

There Flash and HTML5 have a big advantage over any
local download/install solution.

Even worse if the player has to download and setup some libraries.

I would look into HTML5 here. (with WebGL maybe)

The physics for an agry bird game does not need a lot
of performance. (When implemented well)

For mobile platforms the best is their native APPStore
solution.
(Java here for Android)