Bob Pape the author of the ZX Spectrum version of R-type has written a book about the experience and has very kindly decided to give it away for free (PDF format) - http://bizzley.com/
I haven't got around to reading it myself (I've just found out about the book) but it should be a good read if you've got a bit of love for the old games, there's some lovely sprite from the speccy conversion of Rampage in the extras section of his site too
As for sprites... I used to use a util called 3-in-1 Editor for the C=64. I remember well the work that went into creating many sprites for use in demos and games. Nothing that was ever published (Firebird and Ocean both wanted sound adding in which was beyond me and my mate), but I think I still have the cassette with the data on it.
Though he does manage to refer to David Bell and Ian Braben at one point.
Most games have some sort of paddling-pool-and-water-wings beginning to ease you in: Oolite takes the rather more Darwinian approach of heaving you straight into the ocean, often with a brick or two in your pockets for luck. ~ Disembodied