ZZT is one of the first games to be released by Epic MegaGames (back in 1991) and while it is only text based it is darned addictive. ZZT places you in a very large world – with the requirement that you locate a number of special keys to allow you to get into the ZZT palace. The really interesting thing about ZZT (apart from the fact that it has a large complex world full of puzzles) is that it is actually built off of an object oriented concept – where each object (centipede, lion, etc…) has its own basic behavior defined – and acts independently of its environments. In fact – when you purchased the full version of ZZT you were given the tools to be able to build your own worlds out of these basic objects.
ZZT runs really well under Virtual PC. You can find out more about ZZT here: http://en.wikipedia.org/wiki/ZZT