My dream involves a procedurally-generated top down game with modest 2d graphics, multi-touch interface, and descriptive (but not taxing) animation and sound effects. Gameplay would be variable and dependent on editors I have ideas for, but several things are possible.
For example, one variation entails: a space opera game including a fully functional and dynamic ship that reacts to external forces (asteroids, incoming weapons fire, extreme radiation, gravitation, etc.), including all of the interdependent subsystems (propulsion, electricity, computer network/systems/communications, air filtration, water filtration, etc. etc.) and their accompanying crew. A sliding scale between current technological capabilities and futuristic capabilities essentially sets the difficulty level (earlier = more difficult), and mission complexity increases as you go back in time (the parameters for a mining mission or a rendezvous aren't as stringent if you have an AI autopilot, for example). Include random events in a deeper world - pirates, aliens, cannibals, etc. - include realistic emergent behaviors among all entities - sad astronauts, suicidal officers, heroic enlisted men, etc. - include an easy-to-use interface - on my Android tablet, say, one touch to see a menu on any single entity, and either drag for personal entity data or multitouch for commands.
Other possible ideas through the editor:
A realistic zombie sim, including herd and population movement, a simplified form of natural section to develop the breed (and increase difficulty) over time, allowing for a simple farming system for sustainable enclave-making, a simple mining/scrapping/salvaging system for tool-making, vehicle creation, trap-making or fortification.
A fully generated city under the control of an authoritarian regime, but you've got the keys and everything's destructible - break through doors, steal identities and impersonate citizens, infiltrate the upper echelons of the central power, or take over the black market and bombard the citizens with propaganda to gain supporters and start a rebellion.