If I had a solid dream game idea, I'd be busy making it already. Unfortunately, I just have vague genre's that might prove interesting. Fast-paced arena game that's quite skillbased and competitive, with a tad of fighting game inspiration. Something like Bloodline Champions or Archeblade (both are arena games with very competitive playstyle). Another path would be some completely out of the box thinking game. Such as Ingress by Google's Niantic Labs, which is an augmented reality location data based game - you play it by walking in the real world and socializing with people IRL. Maybe something with Oculus Rift, the virtual reality headset. Though that would require coming up with a convincing control scheme for fully 3D virtual reality.