All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger, may Allah exalt his mention as well as that of his family and all his companions.
Our fatwa is that such an action is impermissible, so long as it violates the terms of use of the game that were contractually agreed to. This is because the basic principle is that one must fulfill conditions that do not contradict the Sharia. This is supported by the statement of Allah the Exalted (which means): {O you who believe, fulfill [all] contracts.} [Qruan 5:1]
And it is related from the Prophet, peace and blessings be upon him, that he said: "Muslims are bound by their conditions, except a condition that makes lawful something unlawful, or makes unlawful something lawful" — reported by al-Bukhari as a mu'allaq narration, and reported by al-Tirmidhi, who said: this is a hasan sahih hadith.
Ibn Taymiyyah said, as found in al-Fatawa al-Kubra: “Conditions that do not contradict the Sharia are valid in all contracts.” [End of quote]
And if an action is impermissible, then its wage/earnings are impermissible. It is stated in the hadith: “Indeed, if Allah forbids a thing, He forbids its price [i.e., the proceeds from it]” — [Ahmad, and Ibn Hibban].
And it is stated in “Kitab al-Funun” by Ibn ‘Aqil: “There is no doubt that it is a position within the Hanbali madhhab that the compensation for anything forbidden is [itself] forbidden... and he argued for the prohibition of compensation for what is forbidden by citing the statement of the Prophet, peace and blessings be upon him: ‘May Allah curse the Jews — fats were forbidden to them, so they sold them and consumed their price; indeed, if Allah forbids a thing, He forbids its price.’” [End of quote]
Allah Knows best.