These are from the archive site, I zoomed in as best I could. Do what y'all want with 'em. A nicer view of Sonic's "forward leaning" sprite, plus other elements. I would love to see a higher rez of the one the OP posted since it is a bit more brighter, hopefully we can get some in the near future.
I think the whole "leaning" thing is misleading: It only has the illusion of leaning because: The resolution yields the screen height to be squashed due to 50Hz (which makes sense, this is a Swedish magazine?). This particular frame is the one frame of the four which has happens to have less emphasis on shoes being in-front of him than behind, and any part of the shoe showing in-front is dark, and therefore is camouflaged by the dark background.
Looking at other images, I think most of the dark backgrounds are close-up buildings, which explains that one yellow background object someone mentioned here earlier. Ah, makes sense. Good eye! :D @Master Emerald: For whatever reason, I figured it'd be easier to have them in a cropped png form. Oh well, now we have both. :P
This has always been a difficult thing to tell given the state of our scans but: I think... the UFOs had a palette change. I think in the earlier prototype, they are using the palette intended for lava. Perhaps it wasn't a rotating palette then, which would explain how they got away with it. Later on, they went with green/blue - the grass palette. (Also hurray minor layout differences. Is that because Sonic could get underneath that right platform? I seem to remember reading something similar in Marble Zone.) I think it's a different palette. Not convinced about the foreground in this example - blue/purple reproduction is a bit flakey in these old magazines.
Anyone notice the rings there? Their angles look as if Sonic just took damage, that could mean that the invulnerability frames were much shorter, or that lava had the same behaviours as spikes
Tried to reproduce that shot in the final Sonic 1 ROM - I don't think you can get Sonic and the rings to be in those positions. But whether it's the spike bug... I wouldn't want to say. It could be that the recovery time is shorter or the rings scatter differently. The background is in a different place though, so that's a thing.
Could very well be the case, considering that it was (on the assumption that this was the intended use of the sprite) going to use a unique sprite for when you died by it, they probably wanted to give lava the special treatment like in water when the player drowned
