i tried on Mess emulator, it falls on basic, showing "Syntax error in 0" - i really wonder the reason of that... - on OpenMSX it seems to run fine (but i actually can't play it, i can’t run Catapult for disabling the joystick, or to disable it on Linux, it is always forcing the move to the up-right direction, making it impossible to play)

btw, is this situation at Mess emulator related to memory paging system? which one is being used?

i have to enter "unplug joyporta" in the OpenMSX console - now i can play it fine!

and yes, it's a great Uridium remake (perhaps far better playable than the ZX-Spectrum version), and the 5th sprite flickering trick seems great (i never knew how to do that and how it works, even from those Daniel Bienvenu tutorials! )

about Catapult, or it is not on the Debian/Ubuntu repositories anymore, or it is now having library incompatibility errors, or having segmentation fault errors (i don’t know exactly which ones are), i think Bifi tried to help me to install via irc, compiling sources and everything, and that was a huge headache, specially considering that i was very dependent of the neatness of Catapult for running OpenMSX (for example, using Catapult was how i used to try V9990 emulation, and without that i'm struggling hugely about adding V9990 support on Boriel’s ZX-Basic Compiler - i only have the libraries started, in "theory", i never could try if they work or not... :S )

I have no idea on how autodetect the toshiba chip. AFIK all the difference is in the way VRAM data are rendered, so no detectable effect is present. You just see another thing....
Not having a real Toshiba vdp, I have no means to do experiments, but if you have any clue and a way to do tests on real HW, it will a pleasure for me to implement a detection routine.

About the FM music, the game has plenty of free CPU time, at least at easy level.
At normal level there are some peaks of CPU load according to the number of enemies and bullets on the screen, but I can optimize many things and I am confident we could find the way.

Only considers that now the meta-tiles for ground obstacles and ground destructible targets are not ordered: the code uses a bunch of cpi in order to spot background collisions for the manta and manta's bullets.
Ordering meta-tiles, all that stuff would be replaced by a couple of CP X.