The greeting "Hanukkah Sameach" wishes its hearer a happy Hanukkah. Other ways to wish someone a happy holiday during Hanukkah are "Chag Sameach" and "Chag Urim Sameach," which mean "Happy Holiday" and "Happy Holiday of Lights" respectively, says ToriAvey.com.
A common greeting for the Yom Kippur season of Hanukkah is "Gmar chatimah tovah" which means, "May you be sealed totally for good." This greeting is traditionally used around the last day of Hanukkah, called "Zot Hanukkah." This is spoken as a prayer over the hearer, because the last day of Hanukkah is considered especially favorable for receiving answers to prayers.