this is a combination of an existing chess game, and the exampleplugin (rename script makes it easy to use as base for new plugin) based on https://github.com/RetroShare/ExampleRSPlugin
Both players must currently select each other and press "play game" - ensure your friend has their chess window open before making a move!
put/clone RetroChess to RetroShare/plugins/ recommend
cd ${YOUR_DIR}/RetroShare/plugins/RetroChess/
mkdir build
cd build
qmake ..
make -j$(nproc)
Then restart your RetroShare. You'll see a chess logo in your chat dialog's tool-bar or home's tool-bar.
send a invite in chat dialog with your friend (peer mode only now TuT)
may not support playing more than one game of chess
may crash RS
may kill your cat, dog, or other loved one.
based on: https://github.com/chozabu/CHESS-in-Qt