The basic idea takes from an old, old game called Gravity Wars which involves two stationary ships arranged between several planets where the idea is to shoot your opponent and the planets have gravitational effect on your projectiles.
I've taken other ideas, mainly from an old RISC OS game called TANKS, although the concepts are similar to those used in Worms, that is different types of weapons.
Currently I have the game running as a short tech demo (~2.4MB) between two players with infinite "split" weapons and a video on youtube from earlier in development.
Small technical notes on the game: it uses OpenTK and is written in C#.
I'm also building as much of the internals of the game in a re-usable fashion so I can use them in other projects as well, as I'll explain in my next post.