I promise you that everything has been observed as a professional gamer!
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My system is also powerful, so I am surprised by this game, especially since it is designed with a relatively light Unity engine!!!
Bro, I'm gonna be real with you. I have been building custom PCs since 2004.
I built 15 customs PCs from 2004 to date, some for me and others for friends and family.
I bought some laptops and already built PCs as well.
First thing I do is Furmark and Prime95. This is a common practice. If it gets too hot, I will immediately contact the person/company who built the PC/laptop because it means the device is throttling and I'm getting reduced performance. It also means that the person/company who built it were to lazy to do these tests themselves before handing over the PC. Good builders always test AND stress test. Of course if I built it myself I'll just fix the issue.
I stopped overclocking about 10 years ago but I do stress testing before OC'ing (and after).
Clean the fans and if it is not fixed, you need to add more fans. Watch for air flow, and then decide on which fans should blow air in or out. Watch for any blocked or partially blocked fans, yes I'm talking about bottom-side useless fans. Also watch-out for any adjacent in-out fans. Also look for any fans that are not working.
For gaming laptops, you need to use fan-stand after cleaning if it is still hot. If issue persists you might wanna underclock it a bit.
If you decide to ignore this issue and blame it on the game, you will have the issue again later on another game and you don't want to burn your own PC because it is not properly throttling.
And no, unity is not small engine = faster game. If anything at all, small engines = less optimization. Especially from Indie developer in Beta version.