In 2007, the indie developer messhof created FLYWRENCH, which I felt was a very interesting game. I recommend that all game designers play it. You can download FLYWRENCH here.
In February 2008, I created a game prototype called Nicewrench, which was about experimenting with FLYWRENCH’s design: what happens if you take a game that is about mercilessly killing the player, and remove the possibility for player death?
You can download Nicewrench on my game prototypes page, here.
Both FLYWRENCH and Nicewrench were shown (and played by a room full of attendees) in my presentation at Nuances of Design 2008.
There’s more in the way of design musing in the README, which is also copied here, after the fold.