I bought two hundred dollars of games the other day (I got a working PS2 at last). I thought to myself, why not?
Shiren the Wanderer is a very simple Roguelike. There's no such thing as character generation, the map generation is very simple, and the items are very limited. It's a very limited game.
But it's a lot of (casual) fun!
The reason for this, I think, is the way that the game focuses on the world. Sure, improving your avatar is important, but it's more of an enabler than a reason to play. In theory, the idea is to reach the end of the final dungeon and win. That's never going to happen - it's a roguelike. The end of the dungeon is for hardcore players only.
But along the way you'll run into a large number of "mini-goals" that permanently change the state of the world. Saving a little girl, escorting a chef, that sort of thing. They are generally difficult, but not out of reach. When you accomplish them, the world changes a little. It's a good reason to keep playing.
I've been talking for a while now about using this kind of method. Shiren uses it, and it works. I'm happy to see that it works. Sort of verification by third party experiment. :P