A diamond in the rough...
It's very odd actually, there isn't much you can do besides train and fight, and once in a while play with your monster. It's interactive, but somehow also addictive. Completing tournaments to climb up the ladder to Monster Rancher fame, or fall short because Rockgeiger flicked you or because "Kitty" gives a great reputation to Pixies... something that was very easy to defeat back in the days of Rank D.
The battle system is amazing. There are four kinds of attack, long range, semi-long range, semi-close range, and close range. I hope I said that well. Your monster starts off with two attacks, but more can be gained by going through the Errantry system. Battles as you will find become very exciting and on the edge of your seat, especially when you know your opponent can take you out with one hit, or when the battle is very close and you win or lose by .1% .
There's lots of monsters to unlock and discover, and the game itself... isn't easy to master. I personally haven't even passed the S Rank, I always get there and then my monster dies a few months after. This game is truly "a diamond in the rough" because at this time, it was overlooked by the Pokemon Series. Very unfortunate for the Monster Rancher series.