Actually, those rips have been rescaled or something; there are far more different colours than in the actual sprites.
These rips from the EU Megadrive version are very similar to the Amiga, though one or two colours have been added and the palettes altered.http://www.spriters-resource.com/genesi ... eet/36844/http://www.spriters-resource.com/genesi ... eet/42074/
The Japanese ones are what I found before. They've all been heavily recoloured, and they're a bit odder for it:http://www.spriters-resource.com/genesi ... eet/41905/
Also, some notes on mine compared to the Amiga - mine is the full 320 pixels wide, whereas the playing area on the Amiga is only 288 pixels wide.
The place I've grabbed the sprites from also had twice as many frames of animation for the player - the Amiga version only has six frames for the run and looks jerkier.
But I'll cut mine down to the same number of frames as the Amiga and mirror them too, to run both ways. I've also found the proper bat on that sprite sheet above. Not sure yet whether to pre-shift him or shift him when drawn - probably the latter. Since on mine he has to be masked into all four bitplanes I can use more than just the 3 colours of the Amiga sprite too. I'm also going to try chopping the scenery into smaller blocks (down from 128x173 to 128x22 pixels) so I can try and fit more backgrounds into memory in one load.
I think I'll keep the screen 320 pixels wide, but I have just done some cunning meddling with the mountains to make them repeat after just 240 pixels, to cut down on what I store pre-shifted. Though I'm willing to bet no-one would have noticed if I hadn't mentioned it!