If you use depth, a third axis, it's no longer 2D. If you read this unity tutorial you may understand =>
http://www.third-helix.com/2012/02/05/making-2d-games-with-unity.html
However, to get to the point quickly look at this image from the same article =>
If you're talking about what a 3DS is doing, a pop out effect, then I believe that is possible since you can give each eye a separate light source. A while ago there were talks of Nintendo supporting HTML5 games on the 3DS, https://www.scirra.com/forum/nintendo-to-allow-html5-games-on-wii-u-and-3ds_t81211, Not sure what happened with that other than getting the Wii U exporter.
If you want to get a C2 game on the OR you can do so with NodeJS => https://docs.google.com/document/d/1qICpwaL8WoJFxkXsSIJOcBZ9lnnNQvd_wYTYUMxPVjQ/edit (Not sure who wrote this document, but there are probably more out there if you search for it). However, it will probably be as flat as a pancake, but not sure as I have never used the OR SDK.