The game is currently being programmed for PC and Mac. We're also aiming to make a smartphone version. If we can hit our Wii U stretch goal, we'll be able to afford the extra development time, costs, and dev kit for the Wii U to make the eShop version a reality! This version will launch at least as soon as the PC/Mac versions.
We'd love to have Tadpole Treble be on as many playable systems as possible, but time and money constraints make that difficult. Since we've been getting a lot of requests about Linux, that would likely be the next OS we could make it for. While we love the 3DS, that one would take a little more work in redoing the visuals and screen ratio (not being widescreen means less time to see the upcoming obstacles, for instance), so it may not be feasible just yet.
Of course, we're not ruling any systems out yet at this point, but everything beyond the initial PC/Mac versions will require extra work.
Anyone who buys the game through this Kickstarter will be getting any one version of the game of their choosing.