EDIT: I actually have played this game more like 300-400 hours, instead of just 30. It just didn't get counted through the fact, that I had to start this game manually via it's own .exe, as Steam forced it to crash.
Somewhat complicated to get into, but totally worth it, once you understood everything.
It's the only game that really deserves to be called "global strategy".
You can play every nation during the begin of and throughout the Second World War. (And by that I really mean EVERY nation. It doesn't matter whether or not you want to play as Panama, Australia, USA, Germany, Argentina, France and so on and so forth. You can really play every nation.)
As stated before, however, it doesn't give you a tutorial of what to do. You have to figure all of that out by yourself. There are a lot of Tutorials or some Let's Plays online though, where you can see how the game is played.
From politics, diplomacy and trading over research and espionage to strategic planning, fighting and maybe even couping a country, you can do everything. (Or you can decide to let one thing be controlled by an AI, where you can decide which policy it should follow, so that you can focus on the other things more efficiently.)
It's also quite open to modding and a lot of mods exist already. (You can also rather easily script your own events to make the game more historically accurate or to give it a complete alternative history twist.)
I highly recommend it, as long as you are looking for a good strategy game that is really pushing you to the limits in terms of strategy. (Not in terms of mechanics though, as games like StarCraft2 are doing, for example. That simply wouldn't work out well in this game. It's not competetively oriented.)