Mass: the Effecting/Rogues Gallery
Contained herein are sample opponents who can be picked up and used, or customised if you have more time.
Organics
Shooters
Synthetics
Geth
Geth are a synthetic species who comprise two parts: runtimes and platforms. Runtimes are the actual intelligence or "software". Platforms are the bodies used by the runtimes, or "hardware" and runtimes can transfer to and from platforms at will (assuming they can get a network connection).
Networking Improvements
Geth share a collective neural network; the more runtimes that are networked together, whether in separate platforms or in one, the more efficient and effective their processing power become.
The geth have a number of platforms, which have evolved over time in response to the threats they have faced.
Trooper
The most basic platform is the Trooper.