Seems obvious to ME, but here's my question:

When a character is hit by a double-6 (a crit), does he also suffer knockback along with the extra click?

It would make sense to me if he DID, but someone here's gotta convince my knucklehead roommate... the rules aren't specific about this.

Well the rules do say that whenever doubles are rolled that the charecter suffers knockback. Two sixes would be doubles.

The rule about double sixes is that the charecter suffers one click of damage.
The rule about doubles is they suffer knockback.

PaxZRake is correct... as are you...

ANY successful roll of doubles would generate knockback.

A Critical Success will generate knockback.

As previously mentioned, all successful attack rolls where the dice come up the same number (i.e. doubles) generate knockback. There are additional rules for rolling a 12 or double 6s. The hit is a "critical hit" which will hit the enemy figure regardless of their Defense value and causes an additional click of damage.

An every-so-often mistake I've seen from newbies is to think knockback amount relates to the double-numbers rolled, i.e., that double 5 will generate 5 knockback.

Critical roll generates knockback equal to the damage done. In that case, the intended damage +1 for crit hit=amount of knockback to take for a double-six roll.

He can but THAT in his pipe and smoke it! Thanks.