Game stage tells you, in rough estimate, how bad ■■■ the zombies potentially can be. This works in simple ways. if your game stage is 1, you cant spawn in a feral cop. not even in wasteland. But you can spawn in a regular cop. Besides from biome, this also follows the POI. a policestation will always have cops, but if your game stage is low enough, they will all be regulars. The version of zombie increases in difficulty, as your game stage increases. Also means, that the more game stage you have, the lesser the chances are for a weak zombie.
I would not put too much thought into the loot stage, but if gives you an estimate of what to expect from certain crates. like containers with weapons and gear. if you ahve stage 1, you will most likely only get armor/weapon parts, even from an infested crate. well, you might get a pistol lvl 1, but thats it.
if you stage is 300, and you open up an identical crate, you will most likely get a maxed out weapon.
This does not include any multipliers from skills, that increases amount of bullets etc.
The cap on loot stage, if a way to tell you that it is time to move into a stronger biome, if you want to get better gear. This is because a stronger biome offers a higher level of loot stage, but also zombies of a higher difficulty.
My personal all time favorite "I hate this zombie", is the feral burned, as it has a high chance of setting you on fire, if your armor is too crappy.
