Here's some thoughts that I wanted to share.
I think the MSX touchpad interface is a very interesting input device for MSX games, because:
- even the MSX-1 standard includes it
- openMSX for PC supports it (maybe other emulators as well, I didn't check) through the PC mouse
- openMSX for Android supports it through the Android device touchscreen
The last point suggests the possibility to build MSX games that can be very naturally playable on smartphones. Probably such games should provide also support for traditional inputs (keys/joystick), so they are still playable on physical MSXes without touchpad.
Some game categories fit better than others: for example, it sounds nice for games that
- need elements to be chosen on a board, like many chess/board games
- need a cursor to be freely moved around, like drawing programs
Here's a short test I did for curiosity. I have put this BASIC program on a .dsk file:
10 DEFINT A-Z 20 COLOR 15,4,7: SCREEN 2: KEY OFF 30 SPRITE$(0)=CHR$(224)+CHR$(192)+CHR$(128) 40 B=PAD(0): X=PAD(1): Y=PAD(2) 50 PUT SPRITE 0,(X+B,Y),15+B,0 60 IF PB<>0 AND B<>0 AND (PX<>X OR PY<>Y) THEN LINE (PX,PY)-(X,Y),1 70 PX=X: PY=Y: PB=B 80 IF INKEY$="" THEN GOTO 40
and have run it on openMSX for Android; I needed to
- set in the menu "Hardware" => "Connectors" => "MSX Jostick port A = touchpad"
- adjust slightly the touchpad-to-pixel mapping: open the openMSX textual command console (not the menu), and type "
set touchpad_transform_matrix { { 300 0 -30 } { 0 240 -20 } }"; your device might need slightly different numbers, experiment a bit
and it worked properly, so with eight lines of BASIC you can have your own Android drawing program 
Open questions are:
- does it seem an interesting idea for you too? would you like to see some next year's MSXdev entry supporting touchpad?
- would some already-existing game be better with touchpad support? (example: I think "BeTiled!" would be a good candidate)
Any opinion or further elaboration is welcome! Kindest regards,
Andrea
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