Yes, I tried it about a year or so ago, just one or two scenarios to get my feet wet and get a better idea of what FCS was all about. It has some nice 3-D graphics but the scenarios are somewhat easier than what you'll find in ATF or AATF. That means I could succeed in them without too much trouble whereas in ATF or AATF I typically have to cajole tactical hints out of the game developers and even then the scenarios are challenging. The game also had one or two minor bugs that may be fixed by now, but they were nothing serious and could be worked around. If I recall correctly, it also has a 2 1/2 D display at larger map displays, something I'd love to see incorporated in a future AATF.
It is free and does you give you a nice idea of the different vehicles in the proposed FCS. I'm still personally skeptical that it will all work so well especially against insurgent or guerrilla forces. It still seems better suited to fighting more conventional armies, although the deployable sensors and UAVs will of course help against the asymmetric forces. But I'd still think these would be nice large large targets and insurgents will have superior intelligence of local terrain, culture, and language; and given the use of AT weapons by Hezbollah in Lebanon I don't know if this is the right way to go for asymettric warfare.
I'd be interested in contrary opinions. I'd like to see more FCS scenarios. I understand there is some in Raging Tiger. In one of the proposals I wrote for ARI they suggested using an FCS domain rather than the ATF domain I used, so I should learn more about FCS.
P.S. I didn't know what an RPO was so looked it up. That looks like a nasty weapon. Do we have anything like that in the works, or in the field, flame rockets, or thermobaric weapons, anyone know who can talk about it?