Birthday Boy

Birthday Boy and Cat Shit One are both short anime about war done in CGI. Cat Shit One concentrates more on action while Birthday Boy is more of a slice-of-life though, but they're still rather similar.  

Both anime show a realistic depiction of war through the eyes of children. Even though the art styles are different, both anime have similar imagery, depicting destruction, tanks and airplanes in a war zone, and use the contrast between the purity of children and the hell caused by war to give their message to the viewers. 

Both anime show a realistic depiction of war through the eyes of children. While their length and art styles differ, both anime show similar imagery of destruction and weapons of war, and give an anti-war message by showing the tragic way they can affect people, especially civilians and especially children.