I'm near to starting an AR project that needs to support both Android devices and the HoloLens. I'm planning a tabletop game with minimal tracked objects and likely a LeapMotion to recognize hand gestures. What SDK (or combination of SDKs) exist that support both of these devices with (as much as possible) a single codebase? 

I'm very new to Unity and game development. From my reading, it sounds like the Vuforia+Unity+Windows 10 SDK combo should do it, but it's not clear to me how much platform specific code would be involved or if I would need two entirely separate code projects.

I'd also appreciate any intuition related to:

• how these SDKs relate to each other (eg. what does Vufori add to Unity)
• what sort of code is device specific
• other recommendations for SDKs that support both platforms

I'm a VR developer working with Unreal Engine 4. I've worked with Leap Motion and Android + GearVR, and very briefly touched the hololens for a weekend at a microsoft sponsored hackathon. There's a couple problems with your intended use for hardware platforms.

1) The leap motion requires a USB connection and as far as I know, the current generation of hardware doesn't support mobile VR/AR. The next generation will be built into the HMD, but that may be a ways out.

2) Hololens already comes with gesture recognition. It's not close to as good as Leap Motion.

3) If you're also targeting android for AR, you're going to be using the camera for pass through AR (similar to pokemon go). That means people are going to have to hold the phone at the same time. If they're holding the phone, how will they also do hand gestures? Also, most android phones come with a mini USB port, which is usually used by an HMD.

If you're sold on AR but are a novice as you say, my recommendation is to start super simple and just support one platform for now. Choose Unity + Hololens and get some experience working with the hardware and medium. You can always add complexity later.

Those are some great insights! I appreciate it very much!

Unfortunately I have to support both platforms ;). It's for my Master's thesis, and I'm doing a comparison between HHDs and HMDs.

Concerning the Leap Motion:

- I definitely hadn't thought the USB port issue through, however, I'm planning a collaborative game, so I'll have a server that can hopefully expose necessary leap motion stuff over of service.

- I'm planning on implementing multiple UIs for the different devices, so the gesture stuff will be more aimed at HMDs, but I haven't ruled out trying one handed gestures for HHDs.

Would you suggest Unity with or without Vuforia?