You can't use Geoduck with SLASH'EM Extended - the game doesn't support tilesets. In order to change the font size, check the settings of your terminal emulator; it is not being set by the game itself.
By the way, current version is 1.9.3, and while I admit that the wiki page doesn't give a lot of information about what's new, the project's Github repository shows all the latest changes in chronological order:
https://github.com/SLASHEM-Extended/SLASHEM-Extended/commits/masterThe game can also be played on the em.slashem.me server by connecting with a telnet program (example: PuTTY), port 22, SSH connection. And the #em.slashem.me IRC channel on Freenode can be used for game discussion, there's usually always at least a few players online.