Mama Llama
Mama Llama was somewhat controversial when released, due to a rather unusual control mode. Instead of firing bullets at the enemy in the traditional manner, one offed the baddies with a floating drone kinda a thang. ML also introduced the idea of nonsequential level structure - the player could more or less choose his own path through the game. Other devices allowed the player to decrease the difficulty of known bastard levels, or skip levels altogether.
On account of being so strange, some of the more narrow minded game reviewers slagged ML off considerably. However I didn't give a toss, as I knew that the game was a good one nonetheless, and I got a lot of mail from people who actually played the game affirming that those particular reviewers definitely did indeed have their heads firmly inserted up their own fundaments.