Boulderdash, released in 1984 by First Star Software was one of the classic early c64 titles that pretty much every C64 owner must have played at one point or another.
Graphically Boulderdash was fairly average, with modest sound effects but gameplay back in the 1980's was king and Boulderdash was no exception. You controlled your character called Rockford around caverns filled with rocks and diamonds and had to avoid enemies whilst collecting the diamonds to progress to the next level before the air in the cave ran out. Each level got progressively harder with more varied enemies and harder areas to get around.
I must confess I was never that good at this game as a kid and can never recall getting much further than the 4th level but always remember enjoying playing it.
The character Rockford became more popular than the game itself at the time - he was a character that was used on the much loved C64 magazine Zzap64. An artist used to do little doodles in the page margins and used the Rockford character in amusing situations.
Not quite as good on replay as other games i've recently played again, but certainly another one to add to a c64 collection.