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.
What you mentioned about the factions in a game belonging to non-Muslim civilizations does not entail that playing that game is forbidden. However, it is better to avoid such games in this case. Generally speaking, it is better for a Muslim to spend his time in what benefits him; time is too precious to be wasted in playing such games. Ibn ‘Abbaas related that the Prophet said: “There are two blessings which many people waste, health and free time.” [Al-Bukhari]
For more benefit, please refer to Fatwa 86533.
Allaah knows best.