The following is my humble opinion based on Scripture.
In the first Corinthian epistle, Paul addressed the question of whether eating meat that was served unto idols (after the sacrifice, the meat was sold in a market at a discount) was a sin. This was his response:
1 Cor. Ch. 8 KJV
4 As concerning therefore the eating of those things that are offered in sacrifice unto idols, we know that an idol is nothing in the world, and that there is none other God but one.
5 For though there be that are called gods, whether in heaven or in earth, (as there be gods many, and lords many,)
6 But to us there is but one God, the Father, of whom are all things, and we in him; and one Lord Jesus Christ, by whom are all things, and we by him.
Paul states that since we, the church, know that people serve false gods everywhere, but our God is sovereign and there are no other true gods but He. Therefore, since these gods are simply objects worth nothing more than stone they were carved from, knowledge tells us that there is nothing morally wrong
in itself with the act of eating that meat; the meat is no different than any other meat. However, if we read on...
7 Howbeit there is not in every man that knowledge: for some with conscience of the idol unto this hour eat it as a thing offered unto an idol; and their conscience being weak is defiled.
8 But meat commendeth us not to God: for neither, if we eat, are we the better; neither, if we eat not, are we the worse. 
9 But take heed lest by any means this liberty of yours become a stumblingblock to them that are weak. 
10 For if any man see thee which hast knowledge sit at meat in the idols temple, shall not the conscience of him which is weak be emboldened to eat those things which are offered to idols; 
11 And through thy knowledge shall the weak brother perish, for whom Christ died?
12 But when ye sin so against the brethren, and wound their weak conscience, ye sin against Christ.
13 Wherefore, if meat make my brother to offend, I will eat no flesh while the world standeth, lest I make my brother to offend.
The sin is committed not when one eats the meat, but when a fledgling Christian, seeing us eating this meat that was offered unto an idol, determines in his heart that there is no sin against God committed when one involves himself with the wicked acts of idol-worship. We made our knowledge a stumblingblock to the Christian who was not as spiritually-mature as we are. This is indeed a sin. The key verse for this passage sums up the idea:
1 Now as touching things offered unto idols, we know that we all have knowledge. Knowledge puffeth up, but charity edifieth.
Our knowledge tells us there is nothing wrong with this act, but when we add Christ's love to the equation, we begin to realize that our actions may send a wrong signal to those "newborn" Christians who are watching us. We should live our lives basing every decision on whether someone watching us would be brought closer or pulled farther away to Christ in his walk.
My point?
Though some of us, in our own knowledge, may see nothing wrong with the use of magic and sorcery in video games, if we add love to the equation, what does it show to you? Can you honestly say that someone watching you and looking up to you as a Christian role-model would never base their feelings on whether the acts of witchcraft and wizardry are sinful on seeing you cast a magic spell in some RPG? You can't say for sure. You may not even realize who is watching you and basing their decisions on yours.
You may say, "Who could blame me for the actions of another Christian"? God would. We should base every decision we make on whether someone watching us potentially could grow spiritually or not. If not, don't do it. It's that simple.
Those of you who said there is nothing wrong with the use of magic and sorcery in video games, ask yourself. Is casting a spell in some game worth possibly sinning against God? It isn't to me.
Sorry if anyone was offended or insulted; it was not my intention.
~Jordan
