noname2200 on 13 May 2009
According to this thread, the Artstyle games (especially Orbient) are high-quality, but the longevity comes more from wanting to get high scores than anything.
Some other games you may want to consider are My Life as a King (I've plunked in about 25 hours, but I really like Sim management games) Bit.Trip.Beat (it's "short," but only if you're really good at it. You're not going to be really good at it for a loooooooong while...) Onslaught (online 4-people FPS) and Bubble Bobble Plus (which hasn't released in North America yet, but would fit).
