Complex sentence: In 2005, he established Fenrir & Co. for the purpose of restarting development of Sleipnir as version 2.x, which has no compatibility with version 1.x.
Split into simpler sentences: In 2005, he established Fenrir & Co. for the purpose of restarting development of Sleipnir. Now the version of Sleipnir we can get is 2.x, which has no compatibility with Version 1.x.