Well, I ran into some problems with squeezing the levels into 512k, so I've re-written the mapping routine, along with the graphics! Theoretically, it will run smoothly, with levels over 100* screens wide, on a bog-standard A500. In practice, I'm having a few issues with the map doing as it's told, but I think I've got a solution
I've moved development onto my A600HD, as the A1200 was giving me a few problems, and hoping for a playable level before the end of the month.
While messing about with the mapping routine I came up with another game, called Minecart Mickey, which is similar to Wheelie on the Spectrum. So now I've got 2 games in parallel development... along with a day job, a 3.5 year old daughter and a new one due in April!!
Thanks for the interest - it's given me a bit of a boost and motivation to get the playable demo done for the end of the month.
*Technically, I can make the levels as wide as I like. The game levels will only be about 6-7 screens wide, but if anyone WANTS a 100-screen-wide level then I may be persuaded!!!