I have just finished an MSX-BASIC version of XOR (originally created by Astral Software and published by Logotron in 1987, but never released for MSX) and sublitted it to the downloads section. While it is awaiting approval here is a link for anyone who would like to have a look (this will be deleted once/if my submission is accepted):
This has proven quite a challenge. The original graphics were 24x24 pixels, so needed recreating as 16x16 pixels. The drawing (in BASIC) was simply too slow to be done each screen update, so I draw the whole level in 4k of unused VRAM at the start (hence the progress screen) and then use an assembler routine to copy the current viewport to the visible screen. I am quite pleased with the result - though there are probably optimisations which could be made (my assembler knowledge is almost non-existent!). The background music is based on the C64 version and uses interrupts (PAL) to keep all 3 channels loaded with 1-bar patterns. This enables the music to loop without a break, but does cause a slight visual pause every now and then. Although I have used assembler to update the map window, the movement algorithms are in BASIC and can be very complex. If playing in an emulator, setting the emulator speed to 200% or above makes it pretty playable - although the background music will need turning off due to its reliance on interrupts.
Level 16 (originally only accessible via the level editor) has been included for completion. Images of other unpublished levels have been sourced and may be converted in the future if there is sufficient demand.
