Although it doesn't fit the mobile requirement you should check out AM2R, it's a remake of Metroid II with updated graphics/some new stuff. PC only though. It's not fully complete but there is a very good demo.
Also Cave Story can be run on a DS using either the ismart or DS Two port of Dingux, though I haven't personally tried it, so I'm not sure how playable it really is. But here is the only video I can find showing a demo on YouTube. Skip to about 11 minutes in.
Also Cave Story can be run on a DS using either the ismart or DS Two port of Dingux, though I haven't personally tried it, so I'm not sure how playable it really is. But here is the only video I can find showing a demo on YouTube. Skip to about 11 minutes in.