Kingdom Hearts Re:Chain of Memories

For this trophy you must create 300 rooms - this won't come naturally, no where near it. If you opened all the rooms throughout your normal story progression you should be looking at nearly 100 opened rooms however which still leaves you with 200 more to get. It would be best to leave this for last, focus on collecting Enemy Cards and grinding out level 99.

Once you feel you're ready to get the trophy, save your game and use all your Map Cards in one go; you can do this by running through an easy world like Traverse Town multiple times or if you only have lower number Map Cards just walk in and out of a world multiple times and use a map card at the first door. If you don't unlock it after this reload your save and just continue your grind for whatever you're doing and try again later.