Update

Enemy behaviour is better and varied. 

• Workers increase income but have little health or attack. Worker II has 4x income and more health.
• Attackers cause damage to enemy units and base (if they can break through). Higher levels have more than 3x and 10x health and attack than the basic unit.
• Dozer has high HP but low attack and moves slightly faster. Useful against workers and basic attackers, and can create paths through your workers.