I added serial link support
to my opensource game called "2Decide"
which is on aminet.
I also made a serial link only
2 player space top down shooter
which I never uploaded unfortunately.
off topic:
I made a 2-? player local intense tag game
which I also never uploaded.
I made several other games
including Droidwars 1,2,3,4, and 5,
which are on aminet.