They have a binding for a GUI system as well as for LUA, ODE, OpenAL.

But at the end I am not sure how good you can make a flight-simulation, a shooter or a racing game.

I think the current set is aimed towards shooters. They have AI, pathfinding and other functions implemented that can be used best with shooter-type of games. May be role-playing games or even FPS-Adventures would be a good possibility.

Besides that they provided a little racing demo. So it might be possible.

The goal of the Lawmaker-team is to create a next-gen engine and to deliver the best indie tool available. They have a quite big team working on it and they seem to love Doom3 and Half-Life2. They often compare their engine and tool-set with the tools from Doom3 and HL2 (and both are FPS-engines).

Their indoor-editor is a mixture of the current Doom3-Editor and a little bit like WED. WED is more easy to learn but the Doom3-Editor and the Lawmaker editor is faster (in terms of work-flow) and more efficient at the end.

CSG-cuts are no problems for those editors. It is even the opposite in the Lawmaker tool. You don't create a hollow block like in WED. You cut the block from the solid world. So there are no walls at the beginning just a hollow space covered by solid mass (after you made your first csg subtract).
And you will cut (subtract) all the next rooms from the solid mass that is around you.
This works very fast at the beginning. There are no un-needed walls.

But after that you can add brushes as well and create walls, block, cylinders, whatever.