Fastest way to get kong hard badge:
1. Only buy badges that increase your xp gains. Whenever a new xp badge is unlocked, buy and wear it.
2. Make sure to unlock all maps so you can find the animal maps.
3. Whenever you see an animal map, complete it.
4. Once you've unlocked the zookeeper badge, buy and wear it for animal maps. For other maps, just wear your best xp badge like normal.
Tip for getting the medium badge without having to grind through this so-called "game": repeatedly build and delete $25 tables and other cheap furniture. Each time counts towards the goal of 50.
Tip for every level: slowly build up all your reactors and tech buildings while keeping plenty of weapons for defense buildings. When you've maxed out all your tech, build some more weapons and push forward until you win.
This is purely an endurance badge.