Really great! When it is accomplished, you could do the MSX2 version as well. 
Very nice progress, really cool!
A couple of details I noticed:
- is the "border" color set to transparent intentionally so that it changes with the background color? or should that be set to black (to prevent the bleeding of blue color below the scoreboard)?
- there is a delay in the instrument used for the main melody of the music that makes it sound a bit wonky haha, I wonder if ti musician wouldn't mind removing that delay, so notes sound on the beat they are supposed to sound, and not a fraction of a second later haha. Really small thing, but I cannot avoid hearing it every time I watch a new version of the demo 
Really great otherwise, it moves really smooth, and it's quite impressive to see all those bullets move smoothly now that it's all getting more and more complex. Nice!
Thanks Santi
The background color of the tiles that have to change is set to transparent, so I can change them all just by changing the border color (they are a food amount, so this make me gain CPU time instead of redefine their color attributes each time)
About the music I'll tell it to Bitcaffe. I'm sure that Gabriel will fix it easily
Hi TomH. AFAIK Manfred Trenz did that way because technical limits. the C64 isn't able to move the entire screen during a vblank so there was some kind of precalculation to uodate the screen and it was necessary reserve time to do it. But I read it years ago, so I'm not sure about it
Santi, AFAIK the border is the lowest plane (well, almost, there are two more, external VDP and default black plane) . All other planes are displayed over the border and setting the background color to 0 let to see the border color (wich is a full plane, not properly a border). Setting the border color to 0 permit to see external sources (on VDPs that have superimpose (so 9918 and 9918/A). See also chaptet 2 of "VDP programmer's guide" from Texas Instruments.
Anyway the transiction effect is used only in the first 3 levels (if I'm not mistaken) so I can get rid of it from 4th level on
Hi TomH. AFAIK Manfred Trenz did that way because technical limits. the C64 isn't able to move the entire screen during a vblank so there was some kind of precalculation to uodate the screen and it was necessary reserve time to do it. But I read it years ago, so I'm not sure about it
It does it on all platforms such as I recall, including in the sequels (e.g. Turrican 3 on the Amiga) but it does seem to be fixed by Rendering Ranger.
