Total Recommendations: 2
Both anime are about a game in an online server. Though the storylines are totally different, a few aspects are quite similar, like: there is no way out. In sword art online there seems to be no logout button. In log horizon they don't even know how they got in their world, let alone mentioning how to get out of it. Through the episodes they get to know their world better, along with new potential ways out. Both main characters are solo-players at the beginning of the story, but eventually they learn that the only way to survive here is to join, or make a guild. Kirito and Shiro are both powerful but mysterious players due to lots of experience before their situation broke loose. This gives them an advantage compared to other players, yet they also struggle with a lack of information or new additions.
Both series have those unexpected and mindblowing moments, and both maincharacters have the same ideal: they think the world as it is at the start of the serie is rotting. They want to change something about that by using something supernatural. The twists in Code Geass are some way similar to those in death note; like a game of chess. In both series the maincharacters make their foes powerless one by one...