I had a vision of an asymmetric strategy game about a war between humans and an intelligent dolphin civilization in the near future. The dolphins are trying to cover the Earth in water to expand their empire by melting the polar ice caps. Meanwhile, the humanshave to fight off the dolphin attackers on the coasts. They are militarily more powerful, but the very industry that fuels the war effort contributes to the dolphins' ultimate plan of melting the ice caps, so they have to either be very careful with the use of heavy industry, or continually research improvements in fuel efficiency and anti-pollution measures.
Dolphins have an obvious advantage in water, whereas humans dominate on land. In the seas, humans use standard naval units, and dolphins use water-filled mecha on land; both are more expensive and vulnerable than units in their home territory. The game will also simulate things like tides, storms, and flooding as part of the water mechanics. Both sides can, as the game advances, create various infrastructures to alter the environment in their favor (humans can dam off bays and rivers or dry up isolated bodies of water, dolphins can destroy these and construct inland waterways.