Some games are rare for a reason. Mr. DO!'s Castle
on the 2600 looks like a game that shouldn't have been
attempted, and for the most part you would be right! The
graphics appear crude and the controls are a lot touchier
than the arcade (in particular, using the hammer to knock
out floor).
However, there is game to be had if you're patient. The
graphics are colorful and the music in the game is quite
nice. Because of the difficulty, it is satisfying when
you do clear a board or two. Not highly recommended, but
fun to have mainly for it's rarity.