The Zen Series games for the Nintendo DS are, as the website states in the footnote on one of its pages:
About The Zen Series
The Zen series of games have been developed for the busy, modern urbanite to aid relaxation. This series of lifestyle games do not contain any violence or competitive elements. Zen games are co –published by Mercury Games and Ertain. Experience the spirit of Zen.
I just picked up the Matchstick Puzzle title for S$29 this week.
Check out the other interesting titles that are available at their website:
Aquarium by DS
Paint by DS
Paint by DS - Military Vehicles
I saw the Aquarium titles at the store where I got the Matchstick but not the Paint by DS titles, which I think is interesting.