R.E.A.R.M. - "Rearmament Expansion And Redesign Mod" is an unofficial Homeworld 2 expansion and it adds number of new interesting and various units.
For some people 10 letters weren't enough, so if you're one of them, this is for you. You can choose between 10 large and 24 small.
Also, there's obviosly a limit for how many times you can use each letter, those are subsystems so you can only have a certain number of them. I've increased it from 3 sets to 4, so each small letter is there 4 times now.