I used to be into Role Playing Games / Dungeons and Dragons - before computers were powerful enough to make simulations of that sort of stuff. I threw out my RPG/D&D stuff around 1992. I have thought a lot about the morality of games and I have thought about making a game that is morally acceptable as well.
I think there are so many games out there that it is more useful to talk about guidelines for when a game is wrong or acceptable. Here are some guidelines I would like to suggest:
There are levels of evil in games:
6. The most evil games tend to start with what looks like an innocent game but they lead some of the gamers into witchcraft, psychic powers, false gods, and satanism. Example: Dungeons & Dragons - eventually they added an entire book on false gods for the players characters to take on. Modern false gods and the true Christ God were omitted. The game makes heavy use of magic - and this came make a game interesting but it can also lead into people experimenting with trying to do real evil magic against somebody.
5. The next most evil games do not involve witchcraft, psychic powers, false gods, or satanism; but they are very focused on graphic violence and/or sexual fantasy images. This could lead a player into real violence and/or inappropriate contentography.
4. The next level of games have only non-graphic violence and no sexual imagery, no false gods, no satanism, no witchcraft, and no psychic powers; however the theme of the game is still warlike. An example might be a game where the gamer is playing the role of general for a war against the bad guys that it is okay to kill. Such a game is not too bad but it could encourage the player to believe that war is good when it generally is not good at all.
3. The next level is like 4 only more innocent - Pac Man eating his enemies, Mario bros getting attacked and losing a life. This is about the level that I tend to use.
I think it is important to teach children that even though killing is fun and okay in a game, in reality it is not fun at all and can lead to a lifetime of regrets.
I have thought about making a game that is even better - the theme is a paintball game simulation in zero gravity. But the paint is used not to simulate killing the opponent but rather to paint them a different color and thus "convert" them to a different team where each team has a color. It is better than many games because it is a conversion game rather than a kill game, somewhat like Christianity and converting unbelievers rather than killing them.