I recommend this Japanese free game シルフェイド幻想譚（しるふぇいど げんそうたん）!

シルフェイド幻想譚 that is a fantasy place called at Silfade Island set in the sky. It is one of my favourite free games. The system and the story is awesome. You can download it on this page:
http://www.vector.co.jp/soft/dl/win95/game/se363424.html
Someone says to you 'you are given 15 days to save the world' at the beginning of this game, so you start the save-the-world things. As you know, in a lot of RPGs the world almost come to an end when you reach the worst enemy, but the end will come in 15 days whatever you do or wherever you are in this game.
Please don't read the following, if you'd like to find out all of what will happen by yourself. I'm afraid the following might lose your spoil the surprise a bit. But not a lot, I think.





I believe I put enough line breaks to avoid ネタバレ that means revealing the content (Japanese people often do that on their blogs), so I'll begin the following here.
You can do anything you like until the end comes. If you don't want to be a hero, you can even take a liberty of doing nothing except stay at the inn and meeting the end there. But the instruction you are given clearly is only 'to save the world', so you should find out what to do next by yourself.
Though you can do anything you like, what you can do is rather limited by time, your strength and money. It is because any of your actions cost time and even several steps toward next location cost a hour. Plus, you are weak and your belongings are few at very first.
I think the wide variety and the limit on your action make this game very exciting. Though that might put make you under pressure a little, the ending and some events after it are very enjoyable.
About this game on Wiki:
http://en.wikipedia.org/wiki/Silfade_series