While top tier publishers haven't put out many games with overt religious themes, several titles have injected a moral underpinning.

Chief among these was the "Ultima" series in the mid-1980s through the mid-1990s. Creator Richard Garriott made role-playing games where, aside from killing monsters and collecting treasures, you also were presented with certain moral quandaries.

Done right, adding a moral element can bring a new dimension to games. Done wrong, it can be heavy-handed and ruin the experience.