As the Apple Mac I'm curently using is a real *ix machine, reminding me of my prior life - when that operating system was still in its infancies. Back then we worked unmanly hours - in the quest of fulfilling both our diploma thesis and our wish to explore the unknown... Nethack was the game of choice in those days - played by numerous players within the computer science departement of the RWTH Aachen. This game had two positive aspects: First it tought me the vocabulary needed to understand Harry Potter in his native tongue (otherwise I would have failed to understand potions, spells and other wizard's speak) and second it was available on every machine I used since then.
Only recently I met the unchallenged champions of the game (aka suru) and found out that the famous blogger Eric S. Raymond authored the Nethack manual... and I still did never manage to find that Amulet of Yendor. Have fun - but be warned: Once you manage to decently play the game, you'll probably never be the same gamer again.