Shoot down every single bandit until the wanted criminal is drawn out. Assassinate the level bosses to proceed to the next level. You will have a wider arsenal of weapons as you progress and the bosses will get tougher.
Be a grumpy dinosaur and spew fire at dragons. Kill them and collect their eggs to recharge your inner strength. Be careful though, if you run out of fire, it's game over.
The robots have stolen our precious McGuffin! Intelligence suggests that it is being kept in a briefcase somewhere in their secret base. Infiltrate the base and recover the McGuffin by whatever means necessary!