The mission statement is very generic:
Gluon Creator is a project which will aim at creating a tool designed specifically for creating games, which is useable by all the artists that make up the team behind them: Graphics, sound, level designers, game designers, coders and all others involved in the process.Some commercial and free software already exists, that fits that broad mission statement.
However the last entry already specializes on a specific type of game. On the free software side of the wall it is probably best to leave out the generic 3d engines and concentrate on specific game engines. (Although nearly all engines state that they are designed to create games with ...)
Those were just from the top of my head. A good start for looking for engines is the Libre game Wiki. To be precise - this page.
The part where Gluon Creator could shine is the creation of content editors and streamlining workflow for game creation. However it is not yet clear how it should deal with the specific needs of different game types. Well, that's the exiting part of starting a new project, one can try to apply the lessons learned in other projects with a fresh start.
