[kbrdm]

Can't remember much, but that strange palette, perhaps, 640x480x16 colors, frogs and gems in caves...

As far as i remember you start in a palace, have a deal with king, princess is here too, then you go into nearby cave slash frogs with sword, collect gems, go back, buy better sword...

I recall king was about to fool you, but that may be just my memory playing games.