Condensed reviewer mode: on. Act of War: Direct Action. C&C Clone. C&C Beater. Explosions. Techno-thriller. Terrorists! Conspiracy! Actually really good. So-bad-they're-good cut-scenes. Should have sold more. Expansion pack!
As well as the usual selection of new units to fill out and help tweak the balances of the three-sides and a new single-player campaign (which sadly dumps the real-world footage of actors), there are two major additions to Act of War's actual mechanics: Mercenaries and Navy combat. They're so important they probably deserve a paragraph each. Carriage-return time.
Mercenaries are a shared-unit type, available via the same building to all three sides. They're essentially expensive, powerful and fragile fast-response units which you pay a set fee for and then pay a low repeating retainer as long as they're on the battlefield. They've got the second advantage of being able to be dropped anywhere on the battlefield as an instant response thing - the further into enemy terrain, the longer the delay until arrival while a mercenary chopper reconnoitres the terrain (it can be destroyed by the way, preventing you from dropping mercenaries on the enemy base). As well as basic types of combat medics or support troops you can, if you research appropriately, hire illegal mercenaries including the techno-thriller classic of a dirty nuclear device in the back of a truck. Mercenaries work, add a new element to worry about in the game and offer little worth criticising. So well done for them.