Can I just be a dinosaur? Or many types to choose from? Make combat souls like in execution (with shoulders buttons for attacks and defense and face buttons for dodge, jump, and stances) but with the added versatility of an Assassin's Creed game (microraptors climbing and jumping through trees a la AC3 comes to mind). Edit: and with the climbing mechanics of Dragon's Dogma/SOTC.
Put me in an open world with dinosaurs to hunt or hide from, food and water sources to migrate towards etc. Give me an over the shoulder olfactory mode that increases depth of field and colorizes scents to visualize strength, distance, wind direction and indication of predator and/or prey.
Let me start as a hatchling and have progression be based on objectives completed or attempted with an emphasis on attempted as the game still progresses whether you won the battle for a potential mate or not. Whether you made it across the wild river to join your herd or not or whether you caught that large prey to feed your pack or settled for a smaller selection and fought off your own for the slim pickings. Edit: Basically, each attempted objective furthers the game/"story"/what have you where you visually age and change. Sort of like a timer-less Tokyo Jungle.
Nah, just give us guns to shoot things.