Yes, KLIK, but the whole point of this suggestion is not to completely stop BOINC processing, but simply to limit its use of the machine so as to allow a game all the resources it needs. Gamers with high thread-count machines who run games which cannot utilise all the machines resources (which seems to be most of them) could still churn out BOINC work while running a game perfectly satisfactorily.

The OP was quite certain just how many CPUs their game required to run well. My own understanding of games is limited to what I've read -- I don't play games -- but I've read many times that they cannot use many CPUs. I assume things are different in terms of GPUs, but it is at least the case that many games work best on a particular type of GPU just as, I understand, grid computing applications tend to favour a particular GPU architecture also.
While it would be wonderful if BOINC could work it out on the fly, the OP knew what their game(s) needed, but BOINC only (currently) has an all-or-nothing setting -- what a waste of resources!
It is certainly the case that it would be ideal if games manufacturers would be willing to supply information to the BOINC devs to enable BOINC to be issued with a control file suitable for the majority of games, but that's probably pie in the sky. It might, however, be something that a group of active gamers (such as the OP) might be able to feed into. Another approach might perhaps be a suitable little program which could be run as part of a game's installation process which could update the BOINC control file to set its requirements. That would clearly involve a lot of cooperation which would only happen if grid computing had a high enough profile, but one can only dream!
Nevertheless, if the feature was available to customise BOINC in this way, who knows?!? I certainly feel that it is something that should be provided in order to at least enable progress in this area.

another way to go, use inclient hotkey aka " Ctrl +2 or Ctrl +4 and so on. "
this was another app that hotkey the usage and force a app to use select value to set settings faster without manual edit.

i can also see other post have script solutions. but that mean i have to fix my version and other wont benefit from it. ( this seem so wrong on many ways, even if it work for just me. but much appriciate ideas from above post entrys. TIA

again bonic dev team should look at this much more, i know many hardcore gamer and they blaim bonic manager for lag in game. ( you will loose alot of next gen gamers they know lesser of computer skills , and you need to learn take advantage on cpu inactive while game requirement take what it needs. ( i dont care if you call it bonic game client but if that was such app i will use it and skip this default client im currently use.

gamers dont need alot of current options, they neeed lesser option and stop bother me with it dayli usage. ( and dont update while im gameing ) i think that a games only rule rest you can take then im not gameing.

i only made last entry so you can understand it better.