Pulling inspiration from here, a British docufiction known as The Last Dragon, or as Dragons: A Fantasy Made Real.

Play as a prehistoric Dragon, secure your territory, hunt, fight and ensure the survival of your species.

-Fight over prime nesting grounds, territory, hunting areas and breeding rights.

-Gather materials to nest, experience flight and aerial battles .

Flight would require the air sacks in the chest cavity to have filled with hydrogen and methane - lighter than air and combustible. Keep an eye on your supply while flying, as crash landings would inflict serious or life threatening injuries. Injuries would add a challenge to the game - land bound and crippled, keep yourself alive long enough to heal.

If the player did well enough, time could progress past prehistoric and into, say medieval times.

Barbecued Saint George, anyone?