MH: TCatS is one of the better WWII strategy games available on Steam.
The game offers a nice balance of the need to balance Trade and Economy and Military Expansion. It is not as in depth as concurrence games like Hearts of Iron, but this makes the game very Casual friendly without losing its charme for core players like me.
You can play as a nation of the given scenario time, by standard between 1936 and 1944 (so around World War II obviously). That obviously includes nations like the Soviet Union, the USA and Nazi Germany, but also stuff like Liberia, Bhutan and Guatemala. Great variety of nations. The weaker a nation is, the harder it gets for the player. (You can also set the difficulty out of 7 different difficulties to make enemy AIs more aggressive and well thinking in battle and allied AIs more cowardly and bad thinking in battle.)
One of the big upsides of the game is the real in depth Map Editor, that lets you change special properties of the map like the size of army and the exact position of cities, but also basic properties like which region belongs to which nation and creating new cities, resources, nations etc. The only thing negative is that the Editor targets towards more casual players. Changing flags and emblems of nation, as well as the relation and the behavior of AIs is only able to be changed by going into Editor .xml files and changing the codes. It lets you create stuff like WWI or Modern World or completely fantastic scenarios, but you cannot change the Planet itself sadly. Id love to play in the world of Dungeons & Dragons, WarCraft, etc., but sadly it is not given.
The BIGGEST upside is the Multiplayer of the game. It is really fun, but first off is the community pretty small, so bring some friends to play MP. Also, you mostly need a LAN device to find the servers, Id recommend playing on a LAN party or using Hamachi or better Tunngle (better networks, server and better stabilized).
Over all a pretty great game, even though the expansion to the Gold version, as well as the also pretty good second part of the franchise, is missing on Steam.
I would give it a 82 out of 100. 90 out of 100 if you are the real Multiplayer guy.