There is only war
The original Perimeter is a pretty decent slice of science fiction real time strategy, a bit like Command & Conquer, and with an emphasis on strategy rather than getting bogged down in tedious details. Emperor's Testament is a standalone expansion pack which is equally interesting, as it actually manages to do something new with the genre and avoids many of standard concepts seen in games like KKND. This one finds the player involved in a conflict with a new alien race, the Harbacks, and as is typical for this type of thing, you'll find yourself engaged in a series of missions where you'll battle it out for supremacy with their forces. The main difference between this and other such games is the lack of focus on combat and more on the actual strategy side of things. You'll spend more time on puzzle-style activities such as mining resources and building, while interfering with your enemy's activities and watching out for them doing the same to you. You've got a fairly complex plot to work through over 25 missions, while the game also features the same destructible environments as the original title. If you're looking for something a little different in an RTS, then this is worth a closer inspection. It does lack the combat focus of most such games, but this is quite refreshing in itself, and the greater emphasis on strategy makes for an interesting experience. It's perhaps a tad too similar to its predecessor, while it may also be a bit 'out there' for traditionalists, but if you're prepared to give it a go, there's some fun to be had here.