Im thinking about getting this game is a mmorpg? or is it just RPG game

It's like an MMORPG, but you'll never talk to another player. It's the loneliest MMORPG ever made.

Alright thanks for the input, there is no voice chat feature?

no voice chat feature, no text chat feature. You are meant to have a sense of community through hints and blood spatters left by other players. Players can invade your world to kill you, or you can summon players to help you.

It's quite the interesting experiment in infusing multiplayer features into a game that still feels completely like a Single Player experience.

edit: not to toot my own horn, but here's a review in which I tried to be informative.  http://www.vgchartz.com/games/gamereviewdisp.php?id=31689

^^^

Voice chat ruins the point of a few features in the game. It's not there but for a decent reason.

No voice chat feature. And it really isn't a MMORPG. You have the ability to summon other players into your world in that specific area.

Honestly it's not the summoning or invading that makes me think of the game as an MMORPG, but the hints and the blood spatters.  MMO's to me are all about a group or community coming together to try and accomplish something, and that is done by the hints and blood spatters that help each person get through the game. 

No doubt it isn't your norm for MMORPG, I just think it fosters a sense of community like an MMORPG.

it's a single player rpg with mutiplayer feautures and gameplay implemented in a way, that it never breaks the immersion of the single player main component

How hard is the game if someone tries to play entirely offline?

You just wouldn't have any helpful hints or blood spatters to warn you of impending doom.  You can still defeat every level by yourself (as I did).