You are playing Adventure Time: Billy the Giant Hunter
Slash and slice your way through the Land of Ooo as Billy the legendary warrior. Wield your giant sword of Nothung. The goal is to cut down each of the beautifully designed world of Ooo into a certain size. Check the meter bar on the bottom. When it reaches zero, you may advance to the next level. But be careful of enemies patrolling the surface and hidden underneath. Dispatch as many foes as you can and earn upgrade points to spend on health, power or weaponry. Watch the animated series of Adventure Time on Cartoon Network.