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.
If the game is permissible in principle, then there is no harm in producing it and earning from it, Allah willing. Many entertainment means include wasting time, and this is a relative matter and it differs from one person to another. Some people are disciplined and do not waste a lot of time (in entertainment), while other people waste so much time. Therefore, if you can adjust the game in a way that a person cannot play with it for a long time, then, this is more appropriate.
Although we mentioned that it is permissible to produce it and earn a living by selling it, when it coincides with the Sharee’ah conditions, yet we consider that it is more appropriate for a Muslim to avoid this kind of earning and look for another way to make a living. If a person is smart enough to produce a game, then we do not think that they it is hard for them to produce other things that are more beneficial and useful to the people.
Allah knows best.