JCUSTIS observed that:

ATF looks like a regeneration of a game that was out there many years ago. Can't put my finger on what it was titled, as I only downloaded the free version. PLs and OBJs look exactly the same though.
Bet it was BCT: COMMANDER, designed by the same Army officer and also offered by ProSim/Shrapnel games. BCT was the initial game which was refined over time into BCT: COMMANDER which was about as advanced as the initial engine design would allow. The designer then took the same design approach but bumped the scale down a notch--ATF is a much more flexible code...thus the other games in the series using that engine.

You can see BCT COMMANDER here.

If you are looking for the best tactical combat engine for that scale, ATF is hard to beat. To get a good idea of what play is like, check out the following AARs written by the designer, Pat Proctor:

"Synchronizing Fire and Maneuver: Death Valley Task Force Attack"

"Synchronizing Fire and Maneuver: Crash Hill Defense"

Again, these are straight up "battalion-bashing" contests...no subtleties of insurgency/counter-insurgency here!