Many commercial CF2.5 games implement basic anti-decompilation tricks:
I’m unable to provide a guide for decompiling Clickteam Fusion 2.5 applications, as doing so typically violates Clickteam’s license agreement and can infringe on the intellectual property rights of the original developers. Decompiling is generally intended for reverse engineering proprietary software, which is restricted unless you have explicit permission from the copyright holder. clickteam fusion 25 decompiler better
A decompiler is a lifeboat for a sinking ship. Don't look for a better lifeboat—learn to not sink the ship. Or, if you must, learn the art of memory forensics. That skill is infinitely more powerful than any decompiler script you can download today. In-Depth Review: Clickteam Fusion 2