Sega Ages

Sega Ages is a series of compilations and rereleases of classic Sega video games across several platforms, primarily developed by M2. The first set of games was released for the Sega Saturn primarily in Japan, and another set was released on the PlayStation 2 in Japan, known as Sega Ages 2500. Some of the 2500 titles were released in North America and Europe in Sega Classics Collection. There is also the Sega Ages Online series on the PlayStation Store for PlayStation 3 in Japan, and a new series for the Nintendo Switch will be released on the Nintendo eShop in 2018. The Sega Ages series differs from most "retro" video game rereleases in that rather than compiling a number of games, most of them contain only one game and are instead sold at a very low price.

Sega Saturn series
Sega released several Sega Ages games for the Sega Saturn in Japan:

These versions of Space Harrier, Out Run, and After Burner II were released in North America and Europe on a single disc called Sega Ages, published by Working Designs under their Spaz imprint in North America. It was a best-seller in the United Kingdom.

Sega Ages 2500
Sega Ages 2500 is a series of budget-priced games published by Sega, released for the PlayStation 2 console in Japan, with each game sold individually. Initially, these were part of a joint venture with D3 Publisher called "3D AGES" (SEGA D3 spelled backwards). These releases were primarily remakes of classic arcade titles with modern 3D graphics and new gameplay features, but also included 2D remakes (the Phantasy Star games) and ports (Virtua Racing and Bonanza Bros.).

Sega assumed control of the project with the release of Decathlete, and the 3D AGES development studio was retired with the release of Phantasy Star Generation 2. At this point, the direction of the series shifted focus from remakes to compilations of emulated titles, and ports (enhanced or otherwise) of classic Sega games. Sega produced these titles themselves, but the actual development work was frequently outsourced to other studios, most notably M2.

The notable exception to this shift away from remakes came with the final release in the series, Fantasy Zone Complete Collection, which included a compilation of classic games as well as a remake of Fantasy Zone II: The Tears of Opa-Opa done in a style contemporaneous with the original. The protracted development of this game took over two years, following which Sega decided to retire the series.

List of complete series' titles
Several other titles were cancelled due to the discontinuation of 3D Ages, namely: Alex Kidd in Miracle World, Bare Knuckle, Sonic The Hedgehog, and Phantasy Star IV: The End of the Millennium.

Sega Classics Collection
A compilation of nine of the Sega Ages 3D remake titles were released in North America and Europe in 2005 and 2006 respectively for PlayStation 2.

Sega Ages Online
In Japan, there are six Sega classic game releases that are available on the PlayStation Store for PlayStation 3 that use the Sega Ages Online label. On May 22, 2012, Alex Kidd in Miracle World, Super Hang-On, The Revenge of Shinobi, Wonder Boy in Monster Land, Wonder Boy in Monster World, and Monster World IV were released on the PlayStation Store for PlayStation 3 in all regions but they only use the Sega Ages Online label in Japan. These emulations were handled by M2.

Nintendo Switch
A Sega Ages line developed by M2 will be coming to the Nintendo Switch worldwide in Q3 2018 as Nintendo eShop downloads. The first ten games will be Alex Kidd in Miracle World, Columns II, Gain Ground, Out Run, Phantasy Star, Sonic the Hedgehog, Sonic the Hedgehog 2, Space Harrier, Thunder Force AC, and Thunder Force IV. Sega plans to initially release at least 15 arcade, Master System, and Mega Drive/Genesis titles for the Nintendo Switch, as well as titles from the Saturn and Dreamcast libraries over time. The service debuted for the Nintendo Switch worldwide on September 20, 2018 with Sonic the Hedgehog and Thunder Force IV.