Stage 0-1, "Common Descent" is the 1st level of Space Invaders Infinity Gene, but doesn't seemingly count as a level.
Gameplay[]
The gameplay is quite simple. It is the normal space invaders, but all white. After a bit of time, everything freezes, and the gameplay changes to 3D graphics.
Meaning[]
Common Descent, in the biology term is a concept of evolutionary biology where one species becomes its ancestor later on in life. This means while playing Common Descent in the game, it has taken the player back to its ancestor, Space Invaders. The Black and White version in 1978 where the franchise started it all. Later on, the franchise evolved into sequels of Space Invaders, such as the colored version, Part II, or Space Invaders 1991. From later on in the game, Space Invaders Infinity Gene takes the player through all the games its been through since 1978 up until 2010 building up its own family tree for over 40 years. For example, when the invaders spin clockwise and counterclockwise as seen in Stage 4-1 "Suppressor Mutation", this was seen from its ancestor or predecessor arcade game, Space Invaders 1991.