@Rod McCarthy
Comodo has a gaming mode that disables alerts. However, if you keep Comodo Cloud lookup enabled, the possibility remains that Comodo will auto-sandbox an Unrecognized game file. For optimum compatibility it is best to enable HIPS Training Mode, install game and then continue to use it for a while (at least a week) before switching HIPS back to Safe Mode. Also, every time you play a game use Game Mode.
Gaming is one of those activities that can be problematic with security softs. And there is no way to know beforehand if a security soft will give you troubles. Finally, there is no general rule that can be applied to all games and all security softs in order to avoid problems. The short of it is that you will have to try Comodo on your specific system to see how it works.
The impact Comodo has on system varies from system to system. However, at the desktop, it is quite light on resources and cannot be noticed except during a Full System Scan running in the background. Honestly, this Full System Scan impact is no different than most other AVs so it should not be viewed as a negative.
As far as protection, Comodo offers a very good base-line protection - especially at protecting the physical system from persistent infection. On the other hand, Comodo's web protections are not 1st rate. The argument being that with the way Comodo works, it is not needed - nor is a 1st rate anti-virus signature detection needed.
As far as web protection not being needed, I disagree with regards to phishing; Comodo will not protect you from phishing. If you are reasonably safe web surfer, then it is likely you will never see any benefit to stronger web protections. In that case, Comodo will work fine.
@cruelsister has a video on settings. It is one of the best settings - once you have set up rules for any safe, but Unrecognized files. To start, I would recommend Safe Mode. I will even go further and recommend clean install OS, then immediately install Comodo and enable Training Mode. Install drivers and desired softs. Run Training Mode for at least a week, then tighten security by adopting
@cruelsister's settings with or without HIPS enabled. IF you use Training Mode, CIS will auto-learn file activity and create allow rules for you. Once you switch to Clean PC or Safe Mode, you will rarely get a HIPS alert.
The problem with Comodo HIPS is its alerts. They are poorly designed - with poor documentation - and lead many novice users to make mistakes. Until you learn how HIPS alerts work, it is strongly recommended that you do NOT use any of the "Treat As..." options.
It is important to learn how to operate Comodo and get experience on how it behaves. You can do that only by using it over an extended period of time.
This only covers a fraction of what a user needs to know about Comodo. Unfortunately, you simply cannot install it, adjust a few settings and then forget about it if you actively use many softs and\or are constantly installing\uninstalling softs.