I've been playing Orisanal flash games for a few years, now, and LOVE them. Quiet, intuitive... genteel, really. And beautiful. Amazingly beautiful.
In a similar vein, the geniuses at NNY developed and released upon the world Snowcraft. Heaven help you if you start. It's darn-near impossible to stop.
( I'd lost the URL, so hat tip to the good folks at Metafilter for linking to Orisinal again. )