Challenges are levels within Warzone Idle where you compete against an enemy AI.
Challenges remain locked until you unlock the auto-conquer advancement in Phase 2.
To access them, visit the Warzone Idle main menu and look for the Challenges tab at the bottom.
Challenges can be played concurrently with a normal Warzone Idle level. They don't interrupt or interfere with your normal Warzone Idle level.
 How it Works
When you click Play, the challenge level will be played out right before your eyes very rapidly. The entire level usually takes less than 30 seconds. However, the in-game time that passes is very rapid, usually many days. If you have an advancement that acts every hour, for example, it will act many times during challenges since the in-game time that passes is accellerated.
No interaction is allowed. You cannot manually conquer territories, upgrade army camps or mines, etc. This is why the auto-conquer advancement is required, as its ability to automatically conquer territories is essential to being able to expand in a challenge level.
You can, however, pause and resume the action via the pause button in the upper left corner. This allows you to inspect what's going on in the middle of a level.
While the maps used in the challenges are the same maps used as normal levels, they are generated using a different algorithm and therefore army counts, asset placements, recipe placements and everything else on the map will be different.
Each challenge level awards 100 AP when winning. The reward is only earned the first time you defeat each challenge level.
This amount is not affected by the advancement that increases AP earned from levels.
 How to Win
The only way to improve your performance in challenges is by upgrading your advancements. If you lose, go earn some more AP, spend it, and then re-try the challenge level. There's no penalty for losing, and no limit to the number of times you can attempt each level.
Some advancements help challenges more than others. For example, the "auto" advancements help a lot, such as upgrading Auto Conquer, Auto Upgrade Army Camps, Auto Sell, etc. Army camp production and Joint Strike advancements work passively and therefore also help.
Some advancements don't help at all. For example, increasing max idle time.
Unlike normal Warzone Idle levels, challenges have an enemy on the map to fight against.
The way combat works is simple: Every territory has an army cost to conquer. Before its conquered for the first time, it is shown on the map, but after it is owned by a player its cost is no longer shown. When a territory is conquered, its army cost doubles. It can then be conquered by another player, at which point it doubles again. This process then repeats. Having the cost rise like this is essential for breaking a stalemate where players conquer the same territory back and forth forever -- its cost will eventually rise high enough that one player decides to no longer fight for it.
Assets (mines, army camps, smelters, etc.) can change ownership during a game. When conquered, they will produce for their new owner. Smelters and crafters can be conquered even when in the middle of working on an item, and that partial progress will be transferred to the new owner.
Recipes and caches never change ownership and are acquired immediately. If you conquer a smelter or crafter that's working on a recipe you don't own, it will immediately stop working on it and the ingredients will be refunded to the new owner.