From Sega Retro
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WiiWare is a service offered by Nintendo for Wii owners. It is similar to the Virtual Console, however deals in completely original pieces of software similar to Xbox Live Arcade or the PlayStation Network.
Sega has only released three games for WiiWare, Sonic the Hedgehog 4: Episode I, Let's Catch and Chindouchuu! Pole no Daibouken, preferring to support rival consoles presumably due to a 40MB limit placed upon developers.
On September 29, 2017 it was announced that the Wii's Wii Shop Channel (Where WiiWare is housed) would be shutting down on January 31, 2019 at 3PM JST/5PM AEDT/1AM EDT/6AM GMT/January 30, 2019 at 10PM PST. The ability to buy Wii Points to purchase games was stopped on March 27, 2018 at 5AM JST/7AM AEDT/March 26, 2018 at 1PM PDT/4PM EDT/9PM BST. In the interim between not being able to buy points and it's closure, you were still able to download items you had previously purchased.