This is a good question.

Apart from obvious things pertaining to content (for instance, avoiding gratuitous profanity or explicitness; falsities; poor ethics such as promoting racism or theft; or slander), it is good to consider one's intention in creating the piece, since the intention will be transmitted through the piece. Of course, sometimes one's intention is entirely practical (such as doing a paid job), or something may seem to have little to no ethical impact, but still it is good to have a sound intention.

It is also good to consider how the piece will impact the world. 

Gaming introduces some specific ethical considerations. While I am not against computer/video games (and in fact find the link between games and religion/spirituality to be quite intriguing), from an ethical perspective, it has to be admitted that games are often intentionally designed to be addictive. Furthermore, there may be impacts, particularly on children, with respect to the attention span, or due to exposure to excessive violence and hormonal/chemical reactions to that. On the other hand, some games are quite useful for things such as learning. So if you want to take ethics into consideration when designing computer/video games, it is worth considering current research and concerns about these things; overall, the effect of digital technology on the brain is still unclear. 

When producing content for social media which promotes a person or product, there is also the ethical consideration (from an Islamic viewpoint) that one should not feed the ego (nafs), and that it is poor ethics to engage in self-glorification or self-promotion (except in specific circumstances, like if one is applying for a job and it is necessary). So one has to balance current social requirements (i.e. living in a culture of "likes" in which many people commodify their image online) with a classical sense of Islamic ethics and spirituality. This isn't an easy yes-or-no question but rather goes under the overall category of intention, keeping in mind that people can easily become confused about their intention and, for instance, post a lot of selfies "for the sake of Allah" because they are involved in a religious cause, whereas it is really just feeding the ego/self. 

Some people consider the creation of art or writing to involve some sort of spiritual inspiration. This inspiration could be from Allah, aspects of the higher world promoting truth from Allah, or elsewhere. If one feels the inspiration is unhealthy (for instance, Iblis), one could take that into consideration. Inshallah this will not be the case with what you create, but possibly it relates to some things that have come into popular culture (such as some television shows) which have had (in my view) socially destructive messages. But of course is not good to get too worried about this as it may cause needless anxiety. I am just mentioning it because it is sometimes discussed among artists.

In any case, there is definitely a need for Muslims to be at the forefront of creating media of all sorts, including books, movies, and games, so it is excellent to be in this field. Media is power, and any power can be used for good or for ill. 

I am sure there will be other responses to this too. 

Happy writing and creating!