As you may have noticed in the attached gameplay teaser video, Drifter is a 2.5D game. This is because the engine it is based on is optimized for 2D movement and it would require a lot more effort to make it work in 3D. I've made the decision to do this to keep the scope of the game manageable and to allow me more time to work on adding fun and exciting things for you to do in game.
I only mention it because there have been a few comments wondering about the decision, and I figured it was becoming an FAQ. That said, there are quite a few space games that have worked well despite being constrained to 2-dimensional movement and I hope Drifter will be counted among them.
I would absolutely love to have Drifter available via. Steam and I will definitely try to get it on there. That said, Steam has an approvals process and there's no guarantee that they'll accept Drifter but hopefully if the Kickstarter is successful that will help make the game more attractive to them!
Rest assured if Drifter ends up on Steam I will do everything in my power to make sure backers who get the game also get Steam keys.
Don't see the answer to your question? Ask the project creator directly.