I'm sure someone else has got a more informed solution, but just to rule out the obvious/easy ones: have you tried reinstalling the game? Have you checked that the drivers for your graphics card are updated?

This seems to happen outside of atlas as well:

Jein (yes + no). You'll want an army composition that can beat your enemy, and for that you need dps (damage per second). Spears and pikes are good against cav and for holding enemy melee; if you have only those they'll get shot up by the enemy's dps dealers. Inversely you can snipe their dps dealers with yours (by default they attack the closest units). [I'll now report you to the mod team for not being a spammer so your noob post limit gets lifted.]

100% 0adopeamine This is even better than the last one.

I meant for defensive building like Forts and Towers. My only purpose is to increase their fire. When the building almost destroyed, the units inside it will come out. So, I think melee soldiers can buy more time than squishy rangers. I know turtling is a lame strategy. However, I'm still opened for more tips and tricks. 

You'll never be able to have flawless code, but you can always build stronger code and better anti-cheat protection. This is the case with maphack, which afaik have been fixed in the latest version. Furthermore, saying that 0 A.D. is insecure just because it's open source is like saying Windows is more secure than Linux because it's closed. Security doesn’t depend on hiding the code, but on how the system is designed and what measures are in place to protect it. Not exactly true. Most—if not all—GUI changes are made by modifying the contents of the GUI folder without even touching the simulation folder. True. And I'm not in favor of enforcing any mandatory system for using certified mods or restricting mods. I'm in favor of making information about which mods are being used by all players in a match (whether signed via mod.io or verified in any other way) available to all players—or at least to the host—of the match. After that, each host can set their own rules. Yes, it’s a big challenge. And yet, here we are enjoying an incredible game developed by a community of developers and players that moves forward in many areas through discussion and consensus.