Children love to play games...but they don't much like to have sight word drills, so combine the two for a winning strategy!
I have not met a child yet who did not like to play games (and win)! I have seen great improvement in sight word memorization by the addition of game playing. You can pick any game your child desires to play and it will be an avenue to improve his/her reading vocabulary! Just put the sight words on index cards (twice each, if the number of words is just a few to begin with), pick a favorite game and have fun! This is not a challenge for your child in that you always want enjoyment to be the number one byproduct. So make sure that this is determined as a "helping game". More words will be memorized if you tell him what he does not know, then trying to make him guess. The next round of using the words will display his mastery of them, just by your helpful assistance.
When playing these games, I always read the words, too, before my turn! It is great reinforcement for your child. No time to do this? Have an older sibling play along, even with his own set of cards to practice.