"Dr. Mario Express is a DSiWare title. It was released on April 20, 2009 in North America and as one of the Japan's DSiWare launch on December 24, 2008. The game is also in the PAL regions under the title A Little Bit of... Dr. Mario on May 1, 2009. The game is similar to Dr. Mario Online Rx and costs 500 Nintendo Points to download.
This version of Dr. Mario has received a mixed reception mainly due to its lack of a multiplayer mode"
Source: Wikipedia, "Dr._Mario_Express," available under the CC-BY-SA License.