the degree of compression with animation can be improved (or not) accordingly with the kind of graphics used.

what kind of graphics? reducing and/or reusing frames can save a few bytes. will you show rooms where characters appear? you can reduce the detail and yet give MORE information. there is an old Spectrum game (Knigh Lore) that had a maze of hundreds of rooms and fitted on a 48k spectrum. the secret? the rooms were drawn using only details: a set of brick on each screen to make the walls, the frame of a door. user imagination did the rest (and does even today) look some pictures:

http://www.vgmuseum.com/images/01/knight.html

that site has some source code from these 80s games and a few comments on the techniques that may be of help.

http://www.icemark.com/dataformats/

hth

orlando