It’s an old-school puzzle game, sort of similar to Sokoban but with many extra elements (like monsters!). There is a modern remake, called Xye which has a few nice improvements (though I can’t recommend downloading, as it’s hosted by sourceforge).
What I really like about this game is that anybody could make their own levels (and using only a simple text editor too!). There was a very active community back in the day, sharing custom level packs (i.e. big ASCII files) and challenges; you can see some of these at this great page.
I’m not suggesting we dedicate a month solely to this game, but it would be great to play alongside a couple of others, maybe.