Many games have data too large for the root fs. Moving the game data to flash vfat partition and making a symbolic link from /usr/share/whatever to mmc1 generally works, but requires user to know the ln -s unix command.

Some games also can take the data directory as a command line argument. (edit) for e.g. uqm -n /media/mmc1/share/uqm/content

I am considering changing my large game-data debs to install to /media/mmc1/share/<gamename> if space is available. I don't yet have a way to pop up a user dialogue during install to ask user for confirmation though.

I'll start a thread in development, as this issue affects a large number of game installs.