I have to second or third or 500-th Wesnoth. Great RPG/strategy game. Frozen Bubble is great for those times when you really don't want to do anything else. I would check out http://game.giveawayoftheday.com/ also for great free games. I would recommend puzzle, word, RPG, and strategy games for children/teens. No need to actually offer FPS's to them; I am sure they will get them themselves if they want to play those.
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I have to second or third or 500-th Wesnoth. Great RPG/strategy game. Frozen Bubble is great for those times when you really don't want to do anything else. I would check out http://game.giveawayoftheday.com/ also for great free games. I would recommend puzzle, word, RPG, and strategy games for children/teens. No need to actually offer FPS's to them; I am sure they will get them themselves if they want to play those.