Having said that I think the best games to go for are "slice of life" type games, ぼくのなつやすみ seems to be a good one although it might be too easy for some however I don't know since I've yet to buy the game due to the cost of importing (might be good for those already in Japan). Also dating sims might be worth looking into, there are ones without sexual content and I would suspect the language to be not so complicated and of the everyday type.