There ARE actually a lot of minor nations that are fun to play.
Let's see some examples:
Hungary - Able to stand well with the support of the Axis, or even on it's own. I always build up a considerable army of 20 infantry, mixed up with 4 armor and some milita units for back up. Around mid-38' I usually invade Czechoslovakia or even Yugoslavia... (sometimes I get to annex Austria before Germany does, tho you need a hell lot of luck to avoid a DoW from Germany or Italy). If you go after the Czechs I suggest you try and make your way to Ostrava thru Bratislava and Brno, thus splitting their territorry and hopefully cutting some of their units off the supply. After beating 'em some more, just take a cozy walk into Prague and get the remaining. VPs
As for Yugoslavia, just try and carve yourself a larger piece of land, preferably on the western parts, then release some "more effective" puppets, like Croatia or Bosnia (or is that Sarajevo?
), then with all haste, gain control over the key provinces leading to the Balkans, and after making a peace with them, you can continue your journey with some easy pickings like Albania, or Greece.
Austria - Now, if you could handle Hungary so fat, Austria will be much more easier to do so, IMHO.
I usually deploy my troops to Chur, and DoW Switzerland immediately, then make my way to Bern thru Zürich and annex them. These actions usually make the Soviet Union declare war on Austria (Germany and the Allies are unlikely to do so, as you are on rather good terms with them (and also with the Ities too)), and this leads to a rather nice chain of events: GER DoWing Tuva, Italy DoWing SU, Romania joining the Axis... etc. -well, at least in my games, although it may not happen the same way to you... you can never know. Oh well, if it seems that Romania is holding her own for a couple of months already, you may try and invade Hungary or Yugoslavia (with your presumerably newly built units), although that's a risky one. I usually wait until the Anschluß event pops up and join the axis, by that date, the time comes for the more successful campaigns against your "weakling" neighbours. (with german AIR or even land support, of course) Or if you feel suicidal you may play tag with Italy. :rofl:
Sweden: Well that's quite an easy one... try and maintain a high intervention policy if possible, join the Axis or the Allies (whichever let's you in first) and invade Scandinavia and the Baltic States later on. (also if you plan to pertake in the axis, try not to take all of Finland if possible, you should leave a small line for them so you don't have to face a front with the SU, oh but don't forget to "ask" the Finns for military access
).
Well that's it for now. Try playing as Norway, Denmark or Portugal if you're looking for a Real Challange.
PS.: I'm not telling these strategies prove to be 100% effective, please note that it requires a great deal of "luck" to avoid DoWs from other (most likely neighbouring...) countries...
