Ensure you have the latest version of Cheat Engine installed.

You can "hack" a version of autoplay by deploying a high-level squad (RPG, Sniper, Assault) on an easy level and letting them clear buildings while you focus on defending with a low-overheat Gatling gun.

Be cautious when downloading .CT files from unverified sources. The official Cheat Engine installer itself often contains bloatware, and community-made tables can carry malicious scripts.