Demigod is very repetitive, and aside from some fancy graphics deep down it's still a bit DOTA, and that's free if you have WC3 or so, far better value for money that because there are loads of great scenario's/minigames for RTS games with a good scenario editor.
I'd expect Demigod to cost a tenner normally, and 2.50 on a sale or so, I don't think it's worth that much more personally.
''GC2, DG''
Probably because not everyone may know what that stands for.