This is considered to be one of the worst Digimon games in existence and is one of the reasons why the Digimon World series died. 

Unlike it's predecessors they change up the genre once again this time it's a Hack'n'slash dungeon crawler. Where you can play up to 4 players. Problem is, is that the game is specifically balanced around the 4 player co-op and no it does not get easier if you play solo. So the game is notoriously difficult and it's a shame as I believe this is Dorumon's first appearance in a main console game for digimon. As well as Alphamon.

Difficult game? Yes. Obscure and challenging unlocks? Yes. Intended to be played by 2-4 players rather than 1? Yup. Grindy gameplay loop? Yeah, a little bit. Do I adore this game because I used to play it with my brother and father as a kid? Absolutely and I'll play through the whole thing again this year on my vacation.