You may have come across news stories about a security vulnerability in games made with Unity and you may witness a lot of patches being rolled out on Steam right now to fix this.
The quick TL;DR is: Crumple Zone is based on an older version of Unity that is not affected. So you're safe to play - have fun! :-)
The slightly longer explanation for those who are interested: This Unity Vulnerability only affects games built with Unity 2017.1 and later, but Crumple Zone is using the earlier 5.6.3 version, so it's not affected.
Just to be extra sure I downloaded the official patcher application by Unity and it did not find anything to patch in the Crumple Zone files.
For the more tech-savvy, if you want to confirm this, you can go into the game files and see there is no "UnityPlayer.dll" in the main game folder next to the exe, which would typically be the affected file. And Unity's "output_log.txt" also states the older Unity version (can be found in "CrumpleZone_Data").
So I hope this negates any worries that you might have about playing the game even though there is no patch deployed.