FAQ 2 is only about pre-existing MATERIALS (sprites/models/music/plugins/frameworks/etc), not about pre-existing games. FAQ 3 deals with pre-existing projects.
The main point of that clause is to allow things like the RPG Maker RTPs and items from the Unity Asset Store, etc. So yes you can use the assets that come with RPG Maker.
You can not use a preexisting game.
Pre-existing materials like RTP and assets allowed. Check.
No pre-existing project like made project before the beginning of the competition. Understood.
What if we made an external tool for a specific project before the contest started? are we allowed to use that tool in our IGMC project?