 If you liked
Code Geass: Hangyaku no Lelouch R2
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 ...then you might like
Mawaru Penguindrum
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If you were to cut penguindrum into 2 seasons (1-12 ans 13-24), it is similar in a way with code geass r1 ending in terms of what happened to Himari and Lelouch.
Also as mentioned before Both anime starts out small and eventually ends up being involved with the fate of the world. Both anime are also about brothers doing everything they can for their sister. Code Geass is more political whereas Penguindrum is more focused on family.