In the meantime, I managed to find a bug-fixed Atic Atac version and put it on the BEEB.MMB file, instead of the previous one!
Thank you for your help, it was very useful.
The hardest part was replacing the game in the main menu, to avoid manual booting with the *DBOOT command, but I eventually found a way.
Not everything went smoothly, but I learned a lot and now Atic Atac is working as it should, no messed up screens, I hope.
Now, I would like to find a way, how to add more games within the main menu.
It currently has 67 pages with 20 games each, which is over 1300 titles, but I don't know how to edit the Menu file within the boot menu.ssd disk image so that it accepts new titles, not just replacing existing ones.
I will try to check more games and see if another buggy versions can be find and replaced, but until then here is the BEEB.MMB file with Atic Atac fix, if anyone wants to try it.
Overal, exploring this Beeb collection is really fun!
http://s000.tinyupload.com/index.php?fi ... 0851131726