I haven't been around in forever... so now the reply is way late.
It's not any kind of point N click stuff. Dark Game Studio is just a package containing various products, like Dark Basic Professional, and other stuff like that.
DB is a command set built in C or C++ if I'm not mistaken, and you can extent it if you know how by writing your own functions/dll's and importing them into your code base.
Dark GDK and GDK.net just give you access to the DBPro commands without having to use the DBPro compiler from what I understand.. like with GDK.net you could make a project in a .NET language (Visual C++ / VisualBasic) and include Dark Basic function calls.. so its like a mix and match thing to use the best / easiest tool for the job.
As for 2D.. yeah you can make pretty much any kind of game you want. Platformers like Mario, CastleVania etc.. or a 3D Game. It's all about how much time you have to learn, how dedicated you are, and how much skill you can develop as a programmer. But it really is a hobbyist language first, which is fine imho.. I'd like to make a 2D scrolling platform game some day, a horizantal scrolling shooter, etc.. Maybe one day something in 3D but its just something I mess with in spare time / when interested.