Jonathan from Gameolith here.
Try launching the game from the terminal - enter "Terminal" into the dash and pick the first result, then enter the following commands:
cd /usr/games/avadon/black-fortress
./Avadon
If the last line of output says "Segmentation fault", it's probably this bug - in which case you should edit the file ~/.local/share/Avadon/Avadon.ini to set your screen resolution manually.