I'm sorry, but neither of you replies are really telling me what I need to know.
-How well does C99/C2 handle having a game take place on a single incredibly large, non-linear 'playfield' rather than having it chunked up into levels?
-How well does C99/C2 handle a playfield that isn't easily broken down into squares/rectangles?
-How is making a Sonic-type engine easier in Construct than in MMF2/Game Maker 8.1, if both of those systems already have full-featured, free-to-use Sonic-type engines available for use?
As for coding -- Once I've got most of the worldbuilding work done, I see no problem in hiring coders to finish off the parts I can't handle myself.