Gametype is "Invasion: Starfall", or you can use regular invasion and switch the attackers to Spartans.
Download the map from my file Share
Welcome to Starfall.
Starfall is an Elite defense invasion map with a very specific theme and experimental gameplay dynamics...
After returning to his own universe at the end of Part 2, Dr. Tim is tired from a hard day's work, and ready to go home.
However, upon leaving the facility:
Dr. Tim soon discovers that spiders from the other universe have invaded his own:
Now it's up to Dr. Tim to save the world...