A Halo mod for the critically acclaimed Sins of a Solar Empire, that aims to capture the fast paced intensity of the Halo series.
A quick map overview showing a game with the Flood enabled. They have a 30 minutes wait timer, so they show up around 2:48 minutes in. It's all downhill from there though, as you'll notice a "snowball" effect take place. This is due to the fact that every planet the Flood captures spawns additional flood raids.
Also, strangely, the replay doesn't show me (the light blue UNSC) expanding at all. Unfortunate, but you can still see me holding my planet at the end by the skin of my teeth.