Empty World Strategy

This strategy is rather known, but its good to learn this if you dont know already. This strategy is used for when all your enemies leave the game. This is a easy win, but some people would leave the game because it would take too long. Well, this strategy will make taking out the enemy bases a breeze.

The Beginning
If your enemies leave in the beginning of the match, and they dont have many buildings or units, then you should immediately get a high CPM (Coins Per Minute). I would go for 120-150 CPM but thats just me. You should get at least 2 research centers and research artillery. During the time that they are researching, you also need to buy a barracks so you can get snipers. During this time, you must build a fort to produce the artillery and maybe jeeps if you feel snipers are too slow. And, if you are on a map where you need boats to get to your enemies bases, take this time to get a naval shipyard and some transport ships. Once the research is completed, you will get at least 2 artillery, and at least 2 snipers (more units makes it faster to destroy each base). Now that you have your units, you bring them near an enemy base. You must keep the artillery away from the command centers and from the enemy units, as the artillery can only attack buildings and it has low health. You then will position the artillery in a zone where you can hit the command center, but they cant hit you. This will make short work of any building. You then will put your snipers in an area where you can hit the enemy but the enemy cant hit you. Once all the enemy buildings are gone and the enemy units are dead, you now need to repeat this process for each enemy command center.

The Middle
If your enemies leave during the middle of the match, and they have more units (heavy soldiers, maybe tanks), then you will do the same strategy as listed above, but bring either tanks or many heavy soldiers to protect your artillery and snipers as neither of them can hit tanks. But if they have no tanks, then you can just use the snipers against the enemy soldiers and use the artillery on the buildings.

The End
If, for some reason, all your enemies are gone in the late game, then your enemies most likely left behind planes, heavy soldiers/juggernauts, and defensive buildings. This is harder to complete, but it is possible. You will do the same strategy as the first section, but if they have planes, you need to have anti-aircraft soldiers and/or anti-aircraft tanks. If you are able to take out their command center without being attacked, then do that. If you have to attack the units before you can take out the command center, then you will need to try to find an area where you cant be attacked by a command center or any enemy units and use your snipers.

Risks

 * If your enemies leave later in the match, that makes it much harder to pull off.
 * If there are any enemies left when you are doing this (only one/two enemies left in the game), it will make it much harder as they can send a army to easily destroy your snipers and artillery.
 * The enemy or a new player could join back at any moment, so you need to look out for that.
 * Snipers and artillery have low health so you need to be careful.