Superb version of a classic boardgame although, as usual, "free to play" means "limited demo" unless you want to pay extra. Games only take about 15 minutes, it's easy to learn, the manual's only a few pages, but gameplay's excellent... the sign of a great game. All you need to know about is movement, terrain restrictions and range modifiers and you're away. The visuals may put some people off (it's hexey, same as the boxed real-life version) but behind that it's a gem. Roll the dice, get symbols that match your target type to hit, destroy units or capture a location to get a victory point medal. Simple but effective.
The only trouble is the pay to play model, imo one of the nastiest money leaching and off-putting things to happen to gaming in the last 20 years. Once the 50 free gold runs out you're stuck with only 2 free maps. It may only work out as pennies to play a match but if they'd sell it as a complete game, drop the "free" tag and the extra payments, it would've been great (and maybe had a larger number of long term players). It's happened with other boardgame conversions such as Ticket to Ride, Smallworld, Catan, Space Hulk, Talisman, so why not this too?
Use the free bits then buy the boardgame until they come to their senses and release it as a full game where you can play to your heart's content without paying extra for the pleasure.