Dungeon! is a TSR game, first published in 1975. My edition is from 1980. It is designed for 2-8 players, ages 8 and up. Game duration is approximately 15 minutes for the easy version and 30-60 minutes for the advanced version. This game is pretty fun and one that my 6 year old son really enjoys. So far we've only played the "simplified" version (which is pretty much for little kids only). In the simplified game you basically wander around killing monsters and amassing treasure (until you have 10,000 gold worth). I don't know what all the advanced version adds to the game, but there are spells and suchlike. The advanced rules may enhance the game, but probably not to the point that adults would want to sit down and play this without their kids.
A new edition called, bluntly enough, "New Dungeon!" was released in 1989. As near as I can tell, apart from embiggening the board and improving the rest of the fiddly bits, the game itself is pretty much the same as the original "Dungeon!" game.
I received an email from TSR's David Weseley who passed along some interesting information regarding this game. According to David, Dungeon! is actually an ancestor of Dungeons and Dragons, and not some kiddie version. David Megarry invented Dungeon! in 1971 and played it with the future authors of D&D. He was rejected by all of the established game publishers (MB, PB, AH, SPI) and could not get it published until D&D had been on the market for some time, when TSR bought it from him for 7.5% of their company stock! Some saw this as a recognition of his status as a "godfather of D&D", others as a calculated move to head off possible lawsuits over who invented D&D. But either way, Dungeon! became a steady seller in the TSR board game product line. The copy shown here is a later edition of the game. The first TSR edition used the artwork from the original prototype and had a smaller box. My edition is also apparantly notable for providing counters that are too big to fit on the spaces on the board. Lucky me.