If you want a good artistic game, I would probably recommend something like Journey, The Unfinished Swan (haven't played either, but have heard good things about them), or even just a game with good art direction like The Legend of Zelda: The Wind Waker or Okami.
For story, I would recommend something along the lines of Xenoblade Chronicles (a HUGE game, so you may want to pass on it if you don't have a lot of time on your hands), which has some pretty crazy plot twists while still managing to stay coherent. It also looks absolutely beautiful -[link]. However I would say it is not the best in the character development department. I would also recommend the Assassin's Creed series or even The World Ends With You. The main character goes through some big changes over the storyline, and there is a lot going on in the background you can find out about after finishing the game.
Thanks for suggestion, I will check them out! Hydris, the game that you have linked to looks really bizarre
Bastion was another that I was advised many times to play, so I will get on that one after BioShock probably.
And by the way, what I meant by "developing imagination" were games with some artistic value and great story lines/character development in them. For example, video games link Counter Strike probably won't fall into this category.
Check out games by Ice Pick Lodge. The Void especially; [link] |Trailer. The art direction/design is absolutely wonderful. The other games I'm aware of is Pathologic, but that game was poorly translated to English, and I'm not aware of a fan translation; and there's Cargo!, which looks quite bizarre, but I've only played the demo.
"benefit in developing imagination" seems like it would be impossible to actually describe. Everyone thinks differently, so while I think Mischief Makers is a totally crazy game, somebody else will probably think nothing about it.
But I dunno, check out Bastion or Cave Story or something, I guess. That's all I got.