Skylanders is a series of family friendly action games published by Activision and developed originally by Toys For Bob. The game interfaces with a "Portal of Power" peripheral, on which players place character figures that then show up in-game as their playable character.
Activision has stated that the game eclipsed 1.5 billion dollars in sales revenue by August 2013, (less than two years on the market) with the third game in the series (Swap Force) released in October 2013. TrapTeam, the fourth entry will be released in the second half of 2014.
New characters/figurines are released alongside each new game that comes out. While many characters are available immediately at the launch of the game, the rest are released in a staggered fashion over the following months.Through the first three games, there have been 80 different characters/figurines developed for the games, not counting "legendaries," palette swaps, and re-issues (which are mostly aimed at collectors and completionists).
Although new characters are not backward compatible with older games, all the older characters are forward compatible with new sequels, and even their stats and abilities are carried forward since that data is stored physically in the figure itself.