@Dvik: if using vdp tricks is not a clean job, why not halfing frame rate (25/30 fps) and scrolling at 2pix per frame?.
I've built some demo on disk and if you want i can send you a quick and dirty example of the scrolling to give you an idea.
In this way you can gain:
- two independent char sets (but you need to reduce the height of the game area from 160 to 128, not a big problem i think), this allow you more freedom in design of charsets.
Actually, using the bitmap you've used for GNG demo i see only 80 different patterns on each frame, and you do not use at all color attributes. this means that you can blit the entire pattern table with 640bytes only.
- the smoothness does not suffer from this and you can split CPU power in two frames.
- all msxes (included you beloved
can run safely this sw)
If you want to take a look of a quick demo tell me, i've send you a .dsk with the binary...