The one big reason that can take away the faith of most people? : Other Christians. I don't let myself follow any of the bad influences of these media. I still strive to live a good christian life, read the bible and attend church as much as I can. I don't let it affect me in any other way. so yes this game is even more modest compare to its prequels. In AoW1 and 2 I remembered they are kind of naked. Sure yea a few units do reveal a bit more flesh but they're not naked or nude in anyway! Heck even in the Nymphs are not naked in AoW3: however I don't find any of the visuals in this game to be seducing/sexual in any way.

You send your people into war for no other reason than to conquer the other ones, you exploit independent city populations or displace them, you bribe people, you lie, you kill people because they look different, sit on a spot you want to occupy, may have cool stuff, or work for the wrong person, you use witchcraft, you excessively terraform the environment, you spread giant metropolises with no regard for natural balance or sustainability of resources, you magically or genetically twist your soldiers very being to make them more effective combat units, you sacrifice entire regiments in ploys for your own gain, you sacrifice other units to save yourself, etc. Just my two cents, though: The whole game is objectionable if you were to place real life morals in opposition to it. Other people can't stand the spiders, so eh.

I don't really get why the OP wants a fictional creature in a game to not seduce other fictional creatures or to wear a bikini, but if that is one of his/her hang ups, that's fine with me. You might cover them in scales instead, but that is neither mythologically accurate or solves anything, because if you were offended that a made up creature wears a bikini, surely you would be offended if said humanoid creature was - in effect - naked, since the scales function as a fish skin.

Mermaids are a bit trickier - giving them full clothes would be realistically inpracticable (they occasionately swim, and you wouldn't want to swim in a full dress or anything of the kind). The person could look like the shady trader from Resident Evil, or a corrupt merchant. Doesn't have to be a ghost really, it could be a 'Rogue Negotiator', and the ability could be 'Persuade' as in talking someone around to your view using bribes and false promises.

Age of wonders 3 nude mods