I'm fed up with battling against everything else in a game to get the idea of a grappling hook working. Its ridiculous. I went from having a cool 3D platformer to a 2D physics based game to support it, and I'm now finding I'm imposing even more restrictions to keep this core mechanic alive. Its not a good enough idea to sacrifice everything else I want to do in a game for.
So, have started a new project, moved all the rendering and framework code in place and am going to go back to writing a third person 3D platform game, with no clear idea yet what the unique selling point is.
I'd like the main character to have a bow and arrow that is implemented well, and play around with different kinds of arrows a la classic Thief but in a more cartoony 3D platformer setting. In fact, the whole idea of Mario 64 meets Thief/stealth genre appeals at the moment. Even the grappling idea can be worked in as long as I'm not trying for a spiderman style, live swinging around plan. The rope arrows in Thief worked well in a conventional first person perspective.
So just brainstorming really, but the first step is to build up a solid physics foundation for a kinematic character controller, rigid-body-shape based levels and the tricky issue of moving platforms. I've found in 2D platform games I've written, moving platforms are a challenge best handled as early as possible if you want them to work well and influence all moveable objects so once I have a solid setup for the player character, some moving platforms and some boxes (probably just non-rotational physics) then I will worry then about how I'm going to write a game that has its own unique thing.
I always wanted to write a 3D platform game and I'm finally now at the point where I can implement sufficient graphics and physics to make it happen, so I'm going to just focus on this for a while and see where it goes.