One shouldn't use the shamash for a disgusting use, and certainly not for levity, by playing cards, chas v'chalilah. (Ba'er Heitiv 573:7)
Certainly, one will have to stand judgement for the terrible sin of playing cards by the light of the shamash. (Kav Hayoshor 96)
Every man that fears the word of Hashem, should keep his sons, from when they're young, from these klipos, cards. (Yesod Veshoresh Ha'Avodah 12:1)
Reb Levi Yitzchok of Berditchev says: Due to our many sins, a terrible breach has been made among Acheinu Beis Yisroel to play with cards. It's a light thing in their eyes, but it's known that in each card there is definitely a big klipa… There are many downfalls from this:
1) You lose fear of Hashem.
2) In my eyes you are definitely a thief.
3) You make yourself tamei with klipos that shouldn't even be mentioned. (Kedushas Levi, Chanuka – "Yadua")
Here we see the greatness of the prohibition, and the damage of the soul that comes from playing cards, קרטן (which is the numerical value of שטן)… (Bnei Yisaschor, Kislev 4:90 Hagah)
The Chidushei HaRim of Ger said over the following story one Chanuka night by candle lighting: One Chanuka, someone gave the Chozeh of Lublin a kvitel with the name of a friend on it. The Chozeh looked at it and spit. A while later he handed the kvitel to the Chozeh again. This time the Chozeh looked at the name and said: "this person is illuminating the world". He then added: "before, when you handed me the kvitel, your friend was playing cards; now he's lighting the Chanuka menorah." (Sipurei Chassidim)
I am defiantly not one to tell people what they should or shouldn't do; everyone has their own yetzer hora and I don't judge anyone. HOWEVER, don't come and try to make it into a religious thing to go play cards on Chanukah. Some people actually have it in their head that this is a special "frum", or perhaps "heimishe" thing to do on Chanukah. The Seforim Hakedoshim, as mentioned above, are pretty straight forward about the terrible klipos that come from playing cards. Ironically, many of these same people run around to mekubalim trying to get rid of the klipos that they brought on themselves. On Chanukah, of all times, when we celebrate victory over outside influences, is the most ridiculous time for one to go and play cards. Besides, it's also the final judgment period; would anyone play cards on Yom Kippur? May we all be worthy of seeing the Ohr Haganuz, the hidden light, this Chanukah. G'mar Chasima Tova!