anyone care to explain Defender of the Crown?
 

i like this mini game the best so far.

however,

why is there a merchant at the beginning(Hogben) that takes 20,000 from me but sells nothing in return?and how are the medals calculated in this mini-game? there is NO in game description.

any info would be appreciated.

I went and cleared the first island before talking to Hogben, and upon paying the 20k he gvae me a bunch of medals after a very easy battle.

I'd suggest levelling up a little before talking to him, that should allow it to work.

If I remember correctly he gave me a bunch of medals after giving him my gold even before leveling up. Didn't pay attention to what they were or if they do anything as I quit the game and went back to the orc campaign to try to work throught that instead.

Yes he gives you some medals. If you just to the main quest, this is the shortest campaign I ever played.

Is the some other places to go or must I follow the main quest?

No, there's six fights, or seven if you count the easy one that costs you 20,000