I agree with BadMrBox here. Perhaps the second one doesn't show clearly what you are trying to do. Maybe something in the sense of 2.5D what Pritchard was experiments with few weeks earlier:
http://games.freebasic.net/forum/index.php?topic=68.0I'm really not experienced with this so can't help you design this sort of engine.
But I think the illusion of 3rd dimension can be relatively easily created with skillfully drawn tiles and well compiled layers (background, foreground, etc). That is, if you don't need your player to move between REAL levels, instead of those you would emulate with well drawn tiles.
Also, you can easily convert you old gfx in 24-bit mode, load them up in some drawing program and spice them up if neccesary. I recommend you to use TileStudio for basic tile/sprites handling after that.
Anyway, check out my screen by screen scrolling engine:
http://games.freebasic.net/forum/index.php?topic=12.0It's 24-bit and features some sprite sorting so those higher appear BEHIND those lower, something you might be interested in.
24-bit is not that much different from 8-bit (well, it doesn't have to be) and sometimes it's simply enough to convert your 8-bit graphics to this mode, and then in your engine/game use only small advantages of 24-bit mode, like millions of colors to use (no 256 straight-jacket), somesort of transparent spells (use ALPHA blending for this), emulated lights, simple day/nigth feature, or transparent menus. Not that you can't do that in 8-bit, but you are much more limited and a certain type of palette is imposed on you.